Pneumatic tire

ABSTRACT

To provide a pneumatic tire in which noise can be reduced without changing the basic design of the block pattern.  
     A chamfered portion  24  is provided at a tire widthwise-direction outer side end  18 A of a leading edge  18 A of a block  18 . When the tire rolls and the block  18  contacts a road surface, first, with respect to the leading edge  18 A, a flat portion  22  contacts the ground, and then the chamfered portion  24  contacts the ground. Because the height of the chamfered portion  24  gradually decreases towards the tire widthwise-direction outer side end, the leading edge  18 A at the chamfered portion  24  gradually makes contact with the road surface, whereby force input that generates sound is dispersed in terms of input timing and it is possible to suppress the generation of noise (mainly a striking sound) at the initial state of the block  18  contacting the road surface. Furthermore, by changing the tire widthwise-direction position of the flat portion  22  in a tire circumferential direction, it is possible for the entire block to gently receive stress generated at the time of rolling, whereby it is possible to suppress the level of noise generated by the block  18  at the time the block  18  contacts the ground at a low level.

TECHNICAL FIELD

The present invention relates to a pneumatic tire, and particularly to apneumatic tire that can reduce tire noise without compromising othercharacteristics.

BACKGROUND ART

Tire tread patterns are provided in a tire tread from the objective ofimproving running performance in rain. Because most tire tread patternshave grooves that extend in circumferential and widthwise directions ofthe tire, land portions called blocks are formed in the tread.

However, it is known that pattern noise is generated because the blocksare pvovided.

Conventional technology concerning overcoming pattern noise can belargely categorized into two types.

The first type is a method in which the angle of lug grooves withrespect to the tire widthwise direction is increased, in order to extendthe time during which input is applied to a single block.

The second type is a method in which peaks are not given to a singlefrequency, by utilizing the relation with other blocks, for example, byvarying the circumferential-direction lengths of the blocks or shiftingphases within the same tire tread.

These technologies were mainly developed on the basis of two-dimensionalconception, and their history is long.

However, with respect to automobiles in recent years in which quietnesshas been sought, the effects of the aforementioned conventionaltechnology have not been sufficient. Moreover, because designs thatplace importance only on noise reduction using the aforementionedmethods are not realistic in view of balance with other characteristics,new technology is in demand.

Particularly with respect to a single block, it has been reported that,when the angle of the lug grooves with respect to the widthwisedirection of the tire is increased (i.e., when the pattern design ischanged), block rigidity deteriorates as the configuration of the blockbecomes similar to parallelogram which is long and thin in thecircumferential direction. Further, in this case, partial wear is likelyto occur.

In view of the above facts, it is an object of the present invention toprovide a pneumatic tire in which noise can be reduced without changingthe basic design of the block pattern.

DISCLOSURE OF THE INVENTION

The invention recited in claim 1 is a pneumatic tire including a treadhaving plural blocks divided by plural grooves that mutually intersect,characterized in that height of each block at the leading side edgethereof varies in a tire widthwise direction, a portion of the leadingside edge that initially contacts a road surface being a “highland”portion which is positioned on a tire radial-direction outer side thanthe remaining portion of the leading side edge that later contacts theroad surface, and the highland portion extends in a tire circumferentialdirection and the position of the highland portion in the tire widthwisedirection is changed in the tire circumferential direction.

The action of the pneumatic tire recited in claim 1 will next bedescribed.

When the pneumatic tire recited in claim 1 rolls and the blocks of thetread contact the road surface, the leading edge of the block firstcontacts the road surface at the highland portion (i.e., the highestportion within the leading edge) that is positioned on the tireradial-direction outer side than the remaining portion thereof thatlater contacts the road surface, and then gradually at other portionswhose height is smaller than the highland portion.

Thus, the leading edge of the block gradually makes contact with theroad surface. Accordingly, as the leading edge of the block makescontact with the road surface over time, input that generates sound isdispersed in terms of input timing and it is possible to suppress thegeneration of noise (mainly a striking sound) at the initial stage ofcontact of the block with ground.

When the tire widthwise-direction position of the highland portion doesnot change in the tire circumferential direction, a large load is placedonly on a portion of the block, whereby stress at the time ofcompression increases locally and the level of input is not made small.

However, in the pneumatic tire recited in claim 1, because the tirewidthwise-direction position of the highland portion changes in the tirecircumferential direction, it is possible for the entire block to gentlyreceive stress generated at the time of rolling, whereby it is possibleto significantly suppress the level of noise generated by the block atthe time the block contacts the ground.

The invention has an excellent effect in that noise can reliably reducedin the basic tread pattern having a block configuration.

The invention recited in claim 2 is a pneumatic tire including a treadhaving plural blocks divided by plural grooves that mutually intersect,characterized in that height of each block at the trailing side edgethereof varies in a tire widthwise direction, a portion of the trailingside edge that lastly separates from a road surface being a “highland”portion which is positioned on a tire radial-direction outer side thanthe remaining portion of the trailing side edge that initially separatesthe road surface, and the highland portion extends in a tirecircumferential direction and the position of the highland portion inthe tire widthwise direction is changed in the tire circumferentialdirection.

The action of the pneumatic tire recited in claim 2 will next bedescribed.

When the pneumatic tire recited in claim 2 rolls and the blocks of thetread separate from the road surface, the low portion of the trailingedge of the block initially separates from the road surface, then a highportion of the trailing edge separates from the road surface, and lastlythe highland portion (i.e., the highest portion within the trailingedge) separates from the road surface.

Thus, the trailing edge of the block gradually separates from the roadsurface. Accordingly, as the trailing edge of the block is separatedfrom the road surface over time, it is possible to suppress thegeneration of noise at the later stage of contact of the block withground.

When the tire widthwise direction position of the highland portion doesnot change in the tire circumferential direction, a large load is placedonly on a portion of the block, whereby stress at the time ofcompression increases locally and the level of input is not made small.

However, in the pneumatic tire recited in claim 2, because the tirewidthwise direction position of the highland portion changes in the tirecircumferential direction, it is possible for the entire block to gentlyreceive stress generated at the time of rolling, whereby it is possibleto significantly suppress the level of noise generated by the block atthe time the block contacts the ground.

The invention recited in claim 3 is a pneumatic tire including a treadhaving plural blocks divided by plural grooves that mutually intersect,wherein each of leading side edges and trailing side edges of the blockshas a height that differs in a tire widthwise direction, a portion ofthe leading side edge that initially contacts a road surface being afirst “highland” portion which is positioned on a tire radial-directionouter side than the remaining portion of the leading side edge thatlater contacts the road surface, and a portion of the trailing side edgethat lastly separates from a road surface being a second “highland”portion which is positioned on a tire radial-direction outer side thanthe remaining portion of the trailing side edge that initially separatesfrom the road surface, and each of the first highland portion and thesecond highland portion extends in a tire circumferential direction andthe position of the highland portion in the tire widthwise direction ischanged in the tire circumferential direction.

The action of the pneumatic tire recited in claim 3 will next bedescribed.

In the pneumatic tire recited in claim 3, it is possible to suppress thelevel of noise generated by the blocks at a further low level, due toboth the action recited in claim 1 and the action recited in claim 2.

The invention recited in claim 4 is the pneumatic tire of claim 3,wherein the first highland portions and the second highland portions areconnected such that they are continuous in the tire circumferentialdirection.

The action of the pneumatic tire recited in claim 4 will next bedescribed.

Because the first highland portions and the second highland portions areconnected such that they are continuous in the tire circumferentialdirection, it is possible to suppress noise level at a low level duringthe time from when the block contacts the road surface to when the blockseparates from the road surface.

The invention recited in claim 5 is the pneumatic tire of any one ofclaims 1 to 4, wherein portions lower than the highland portions areformed as smoothly curved surfaces whose height gradually decreasestowards block edges.

The action of the pneumatic tire recited in claim 5 will next bedescribed.

By forming portions lower than the highland portions as smoothly curvedsurfaces whose height gradually decreases towards block edges, the treadsurface makes gradually contact with (gradually separates from) the roadsurface, thereby it is possible to suppress the level of generated noiseat a low level.

The invention recited in claim 6 is the pneumatic tire of any one ofclaims 1 to 5, wherein when the blocks are viewed in cross section alongthe tire widthwise direction, the highland portions and the portionslower than the highland portions are provided in any cross section ofportions at tire circumferential-direction positions.

The action of the pneumatic tire recited in claim 6 will next bedescribed.

Because the highland portions and the portions lower than the highlandportions are provided in any cross section of portions at tirecircumferential-direction positions, it is possible to suppress noiselevel at a low level during the time from when the block contacts theroad surface to when the block separates from the road surface.

The invention recited in claim 7 is the pneumatic tire of any one ofclaims 1 to 6, wherein in a tread surface of the blocks, the highlandportions include flat portions that coincide with an outer contourconfiguration of the tire.

The action of the pneumatic tire recited in claim 7 will next bedescribed.

When the highland portion includes the flat portion that coincides withthe outer contour configuration of the tire, it is possible to preventthe block compression amount from increasing, at the same load, due tothe three-dimensionalization of the block surface, as compared.

Namely, when a block in which the highland portion is not flat iscompared to a block in which the highland portion includes a flatportion that coincides with the tire outer contour configuration, theblock in which the highland portion is not flat is a block in which thechamfered portion is large (herein the block is seen as a cubic block),and the block including the flat portion is a block in which thechamfered portion is small (herein the block is seen as a cubic block),so that the volume of the block in which the highland portion is notflat is smaller than that of the block that includes the flat portion.

For this reason, when the same load is applied to each of the blocks,the amount of compression of the block in which the highland portion isnot flat becomes greater than that of the block that includes the flatportion. When a load is applied to the blocks, the blocks are deformedinto a barrel shape, and when the amount of compression is increased,the tendency for the blocks to be deformed into the barrel shape isencouraged. As a result, there is an increase in local stress (ordeformation) near groove bottoms at block ends.

This indicates the deteriorated state of the input. However, it ispossible to suppress an excessive increase in the amount of compressionof the blocks by providing, as needed, the flat portion. As a result, itis possible to suppress worsening of the noise associated with excessivecompression.

The invention recited in claim 8 is the pneumatic tire of claim 7,wherein in the block edges in the tire circumferential direction, a tirewidthwise direction dimension of the flat portion is in a range of 3 mmto 15 mm (inclusive of 3 mm and 15 mm).

The action of the pneumatic tire recited in claim 8 will next bedescribed.

In the block edges in the tire circumferential direction, when the tirewidthwise dimension of the flat portion is less than 3 mm, it becomesimpossible to sufficiently reduce the level of noise.

Additionally, in the block edges in the tire circumferential direction,when the widthwise dimension of the flat portion exceeds 15 mm, itbecomes impossible to sufficiently reduce the level of noise.

Thus, in the block edges in the tire circumferential direction, it ispreferable to set the tire widthwise dimension of the flat portion to bein a range of 3 mm to 15 mm.

The invention recited in claim 9 is the pneumatic tire of claim 7 orclaim 8, wherein in the block edges in the tire circumferentialdirection, the tire widthwise-direction dimension of the flat portion is0.15 to 0.75 times a tire widthwise-direction dimension of the blockedges.

The action of the pneumatic tire recited in claim 9 will next bedescribed.

In the block edges in the tire circumferential direction, when the tirewidthwise-direction dimension of the flat portion is less than 0.15times the tire widthwise-direction dimension of the block edges, itbecomes impossible to sufficiently reduce the level of noise.

Additionally, in the block edges in the tire circumferential direction,when the tire widthwise-direction dimension of the flat portion isgreater than 0.75 times the tire widthwise-direction dimension of theblock edges, it becomes impossible to sufficiently reduce the level ofnoise.

Thus, in the block edges in the tire circumferential direction, it ispreferable to set the tire widthwise-direction dimension of the flatportion to be 0.15 to 0.75 times the tire widthwise-direction dimensionof the block edges.

The invention recited in claim 10 is the pneumatic tire of any one ofclaims 1 to 9, wherein in the block edges in the tire circumferentialdirection, a depth dimension in a block height direction from a highestportion of the highland portion to a lowest portion of the tread surfaceis within a range of 0.1 mm to 2.5 mm (inclusive of 0.1 mm and 2.5 mm).

The action of the pneumatic tire recited in claim 10 will next bedescribed.

In the block edges in the tire circumferential direction, when the depthdimension in a block height direction from a highest portion of thehighland portion to a lowest portion of the tread surface is less than0.1 mm, it becomes impossible to sufficiently reduce the level of noise.

Additionally, in the block edges in the tire circumferential direction,when the depth dimension in a block height direction from a highestportion of the highland portion to a lowest portion of the tread surfaceexceeds 2.5 mm, it becomes impossible to sufficiently reduce the levelof noise.

Thus, in the block edges in the tire circumferential direction, it ispreferable to set the depth dimension in a block height direction from ahighest portion of the highland portion to a lowest portion of the treadsurface to be within in a range of 0.1 mm to 2.5 mm.

The invention recited in claim 11 is the pneumatic tire of any one ofclaims 1 to 10, wherein in the block edges in the tire circumferentialdirection, the depth dimension in the block height direction from thehighest portion of the highland portion to the lowest portion of thetread surface is 0.01 to 0.25 times a maximum height of the highlandportion.

The action of the pneumatic tire recited in claim 11 will next bedescribed.

In the block edges in the tire circumferential direction, when the depthdimension in the block height direction from the highest portion of thehighland portion to the lowest portion of the tread surface is less than0.01 times a maximum height of the highland portion, it becomesimpossible to sufficiently reduce the level of noise.

Additionally, in the block edges in the tire circumferential direction,when the depth dimension is greater than 0.25 times a maximum height ofthe highland portion, it becomes impossible to sufficiently reduce thelevel of noise.

Thus, in the block edges in the tire circumferential direction, it ispreferable to set the depth dimension in the block height direction fromthe highest portion of the highland portion to the lowest portion of thetread surface to be 0.01 to 0.25 times a maximum height of the highlandportion.

The invention recited in claim 12 is the pneumatic tire of any one ofclaims 1 to 11, wherein in the block edges in the tire circumferentialdirection, a tire widthwise-direction length of the portions lower thanthe highland portions is 5 mm to 17 mm.

The action of the pneumatic tire recited in claim 12 will next bedescribed.

In the block edges in the circumferential direction, when the tirewidthwise-direction length of the portion lower than the highlandportion is less than 5 mm, it becomes impossible to sufficiently reducethe level of noise.

Additionally, in the block edges in the tire circumferential direction,when the tire widthwise-direction length of the portion lower than thehighland portion exceeds 17 mm, it becomes impossible to sufficientlyreduce the level of noise.

Thus, in the block edges in the tire circumferential direction, it ispreferable to set the tire widthwise-direction length of the portionlower than the highland portion to be 5 mm to 17 mm.

The invention recited in claim 13 is the pneumatic tire of any one ofclaims 1 to 12, wherein in the block edges in the tire circumferentialdirection, the tire widthwise-direction length of the portions lowerthan the highland portions is 0.25 to 0.85 times the tirewidthwise-direction dimension of the block edges.

The action of the pneumatic tire recited in claim 13 will next bedescribed.

In the block edges in the tire circumferential direction, when the tirewidthwise-direction length of the portion lower than the highlandportion is less than 0.25 times the tire widthwise-direction dimensionof the block edges, it becomes impossible to sufficiently reduce thelevel of noise.

Additionally, in the block edges in the tire circumferential direction,when the tire widthwise-direction length of the portion lower than thehighland portion is greater than 0.85 times the tire widthwise-directiondimension of the block edges, it becomes impossible to sufficientlyreduce the level of noise.

The invention recited in claim 14 is the pneumatic tire of any one ofclaims 1 to 13, wherein in the block edges in the tirecircumferential-direction of blocks disposed at places other than on atire equatorial plane of the tread, highland portions are disposed at atire equatorial plane side.

The action of the pneumatic tire recited in claim 14 will next bedescribed.

When seen in cross section along the tire rotational axis, the outercontour configuration of the tread is a substantially circular arc shapehaving a large radius of curvature.

For example, when a pneumatic tire provided with blocks in which theheight of the leading edges thereof is constant in the tire widthwisedirection rolls, because the leading edges of blocks disposed at placesother than on the tire equatorial plane, in a state of just beforemaking contact with the road surface, slant in the direction in whichthe tire equatorial plane side thereof nears the road surface, theleading edges begin contacting the ground from the tire equatorial planeside.

If the highland portion at the leading edge is disposed at the sideopposite from the tire equatorial plane side, there are cases in which,due to the vertical difference between the highland portion and the lowportion and to the impact of the radius of curvature of the crownportion of the tread, the leading edge becomes parallel to the roadsurface at the time it makes contact with the road surface, the trailingedge becomes parallel to the road surface at the time it separates fromthe road surface, contact is made with the road surface initially by thelow portion of the leading edge, or the low portion of the trailing edgelastly separates from the road surface, whereby it becomes impossible toreduce the level of noise.

In the pneumatic tire recited in claim 14, in the edges in the tirecircumferential direction of blocks disposed at places other than on thetire equatorial plane of the tread, because the highland portions aredisposed at the tire equatorial plane side, it is reliably possible forcontact with the road surface to be made from the highland portion ofthe leading edge of the block in a pneumatic tire provided with thehighland portion and the low portion at the leading edge of the block,and it is reliably possible for the highland portion of the trailingedge of the block to lastly separate from the road surface in apneumatic tire provided with the highland portion and the low portion atthe trailing edge of the block. Thus, it is possible to reliably reducethe level of noise.

The invention recited in claim 15 is a pneumatic tire including a treadhaving plural blocks divided by plural circumferential grooves extendingin the tire circumferential direction and plural grooves that intersectthe circuferential grooves, characterized in that, at end edges on thetire equatorial plane side, of blocks at outermost sides in a tirewidthwise direction, highland portions along a tire outer contour aredisposed at one of a leading side end edge and a trailing side end edge,and first lowland portions whose block height gradually becomes lower ina direction of moving away from the highland portions are disposed atthe other of the leading side end edge and the trailing side end edge,and at ground-contact ends of the blocks at the outermost sides in thetire widthwise direction, all are highland portions along the tire outercontour.

The action of the pneumatic tire recited in claim 15 will next bedescribed.

First, with respect to an ordinary shoulder block 100 shown in FIG. 30,in which the height of the shoulder block 100 is constant, there isprovided a ground-contact region 102 (hatched portion) defined bydimensions A and B (it should be noted that reference numeral 104denotes a ground-contact end, the direction of arrow L and the directionof arrow R denote a tire widthwise direction, and the direction of arrowA denotes the direction in which the tire rotates).

The ground-contact region 102 represents the state of the regionimmediately before the ground-contact region makes contact with theground. In actuality, when the shoulder block 100 receives input or whenthe input is released at the time the ground-contact region 102 makescontact with or separates from a road surface, contact and separationare conducted gradually in the circumferential direction.

Noise input is large at a portion that fluctuates dynamically large.Thus, such a portion is important in terms of reducing noise.

A leading side end edge 100A of the shoulder block 100 defined bydimension B receives an impact of the contact shape with which the blockmakes contact, and contact with the ground is carried out at roughly thesame time in the tire widthwise direction, in a case where the treadsurface of the shoulder block 100 is flat. Thus, a force having a singlelarge peak is transmitted via the end edge to the tire and becomes inputof a vibrating noise.

In the blocks at outermost sides in a tire widthwise direction recitedin claim 15, in the end edges on the tire equatorial plane side, firstlowland portions whose block height gradually becomes lower are disposedat the other of the leading side end edge and the trailing side endedge.

For this reason, block height gradually increases, from the end edges onthe tire equatorial plane side towards the tire widthwise-directionouter side, at the leading side end edge or trailing side end edgeprovided with the first lowland portions.

Thus, when the first lowland portion is provided at the leading side ofthe end edge on the tire equatorial plane side, the leading edge makesgradual contact with the road surface at the time of making contact.Therefore, it is possible to make the input per unit time of the peakforce resulting from deformation (in kicking-in) prolonged for as longas the time required for the input. In this manner, it is possible tosuppress the level of noise generated by the tire widthwise-directionoutermost side blocks at a low level.

In a case in which the first lowland portion is disposed at the trailingside of the end edge located on the tire equatorial plane side, thetrailing edge gradually separates from the road surface at the time ofseparation. Therefore, it is possible to make the input per unit time ofthe peak force resulting from deformation (in kicking-off) prolonged foras long as the time required for the input. In this manner, it ispossible to suppress the level of noise generated by the tirewidthwise-direction outermost side blocks at a low level.

In the tire widthwise-direction outermost side blocks, because all ofthe ground-contact ends on the outer side in the tirewidthwise-direction are highland portions along the tire outer contour,it is possible to maximize the vertical difference of the ground-contactportion at the leading edge or the trailing edge, and it is possible tomaximally prolong the time required for one end to the other end, of theleading edge or the trailing edge, to make contact with the ground (orthe time required for the one end to the other end to separate from theground).

It should be noted that the ground-contact end referred to herein isthat observed when a pneumatic tire is placed on a standard rimstipulated in the JATMA Year Book (Japan Automobile Tyre Manufacturer'sAssociation standard, 2001 Edition) and the tire is filled to aninternal pressure of 100% of the air pressure (maximum air pressure)corresponding to the maximum load capability (bolded load in theinternal pressure-load capability correspondence chart) in the appliedsize ply rating of the JATMA Year Book, to bear the maximum loadcapability.

When the TRA standard or the ETRTO standard is applied in the use sitesor manufacture sites, the respective standard is followed.

The invention recited in claim 16 is a pneumatic tire including a treadhaving plural blocks divided by plural grooves that mutually intersect,characterized in that, highland portions along a tire outer contour andsecond lowland portions that are lower than the highland portions andwhose block height gradually becomes lower in a direction of moving awayfrom the highland portions are disposed at a leading side edge or atrailing side edge of blocks at outermost sides in a tire widthwisedirection.

The action of the pneumatic tire recited in claim 16 will next bedescribed.

According to the pneumatic tire recited in claim 16, because highlandportions along a tire outer contour and second lowland portions that arelower than the highland portions and whose block height graduallybecomes lower in a direction of moving away from the highland portionsare disposed at a leading side edge or a trailing side edge of blocks atoutermost sides in a tire widthwise direction, it is possible to makethe input per unit time of the peak force resulting from deformation (inkicking-in or kicking-off) prolonged for as long as the time requiredfor the input. In this manner, it is possible to suppress the level ofnoise generated by the tire widthwise-direction outermost side blocks ata low level.

The invention recited in claim 17 is a pneumatic tire including a treadhaving plural blocks divided by plural grooves that mutually intersect,characterized in that, at end edges, of the tire equatorial plane side,of blocks at outermost sides in a tire widthwise direction, highlandportions along a tire outer contour are disposed at one of a leadingside end edge and a trailing side end edge, and first lowland portionswhose block height gradually becomes lower in a direction of moving awayfrom the highland portions are disposed at the other of the leading sideend edge and the trailing side end edge, and highland portions along atire outer contour and second lowland portions that are lower than thehighland portions and whose block height gradually becomes lower in adirection of moving away from the highland portions are disposed at theleading side edge or the trailing side edge of the blocks at theoutermost sides in the tire widthwise direction not provided with thefirst lowland portions.

The action of the pneumatic tire recited in claim 17 will next bedescribed.

In the pneumatic tire recited in claim 17, because the first lowlandportion is disposed at one of the leading side and the trailing side ofthe end edge on the tire equatorial plane side and the second lowlandportion is disposed at the other of the leading side end edge and thetrailing side end edge, it is possible to make the inputs of the peakforces resulting from deformations both in kicking-in and kicking-off,continuous in the direction of the direction of the “time” axis (i.e.,both the action recited in claim 1 and the action recited in claim 2),whereby it is possible to suppress the level of noise generated by thetire widthwise-direction outermost side blocks at a low level.

The invention recited in claim 18 is the pneumatic tire of claim 15 or17, wherein in the end edges, on the tire equatorial plane side, of theblocks at outermost sides in the tire widthwise direction, when Hadenotes a depth dimension in a block height direction from a highestportion of the highland portion to a lowest portion of the first lowlandportion, Ha is 0.2 mm to 2.5 mm.

The action of the pneumatic tire recited in claim 18 will next bedescribed.

By setting Ha to be 0.2 mm to 2.5 mm, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 19 is the pneumatic tire of any one ofclaims 15, 17 and 18, wherein in the end edges on the tire equatorialplane side, of the blocks at outermost sides in the tire widthwisedirection, when Ha denotes a depth dimension in a block height directionfrom a highest portion of the highland portion to a lowest portion ofthe first lowland portion and C denotes block height in the end edges,on the tire equatorial plane side, of the blocks at outermost sides inthe tire widthwise direction, Ha/C is 0.02 to 0.25.

The action of the pneumatic tire recited in claim 19 will next bedescribed.

By setting Ha/C to be 0.02 to 0.25, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 20 is the pneumatic tire of claim 16 orclaim 17, wherein in the leading side edge or trailing side edgeprovided with the second lowland portion, when Hb denotes a depthdimension in a block height direction from a highest portion of thehighland portion to a lowest portion of the second lowland portion, Hbis 0.2 mm to 2.5 mm.

The action of the pneumatic tire recited in claim 20 will next bedescribed.

By setting Hb to be 0.2 mm to 2.5 mm, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 21 is the pneumatic tire of any one ofclaims 16, 17 and 20, wherein in the leading side edge or trailing sideedge provided with the second lowland portion, when Hb denotes a depthdimension in a block height direction from a highest portion of thehighland portion to a lowest portion of the second lowland portion and Cdenotes block height in the end edge on the tire equatorial plane side,of the blocks at outermost sides in the tire widthwise direction, Hb/Cis 0.02 to 0.25.

The action of the pneumatic tire recited in claim 21 will next bedescribed.

By setting Hb/C to be 0.02 to 0.25, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 22 is the pneumatic tire of any one ofclaims 15, 17, 18 and 19, wherein when La denotes a dimension of thefirst lowland portion measured from the end edge on the tire equatorialplane side towards the tire widthwise-direction outer side, dimension Lais 5 mm or greater.

The action of the pneumatic tire recited in claim 22 will next bedescribed.

By setting La to be 5 mm or greater, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 23 is the pneumatic tire of any one ofclaims 15, 17, 18, 19 and 22, wherein when La denotes a dimension of thefirst lowland portion measured from the end edge on the tire equatorialplane side towards the tire widthwise-direction outer side and B denotesa dimension of the block at the outermost side in the tire widthwisedirection measured from the end edge on the tire equatorial plane sideto the ground-contact edge on the tire widthwise-direction outer side,La/B is 0.25 or greater.

The action of the pneumatic tire recited in claim 23 will next bedescribed.

By setting La/B to be 0.25 or greater, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 24 is the pneumatic tire of any one ofclaims 15, 17, 18, 19, 22 and 23, wherein when Lb denotes a dimension ofthe first lowland portion measured along the tire circumferentialdirection from the leading side edge or trailing side edge provided withthe first lowland portion, Lb is 10 mm or greater.

The action of the pneumatic tire recited in claim 24 will next bedescribed.

By setting Lb to be 10 mm or greater, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 25 is the pneumatic tire of any one ofclaims 15, 17, 18, 19, 22, 23 and 24, wherein when Lb denotes adimension of the first lowland portion measured along the tirecircumferential direction from the leading side edge or trailing sideedge provided with the first lowland portion and A denotes a dimensionof the end edge on the tire equatorial plane side measured along thetire circumferential direction, Lb/A is 0.3 or greater.

The action of the pneumatic tire recited in claim 25 will next bedescribed.

By setting Lb/A to be 0.3 or greater, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 26 is the pneumatic tire of any one ofclaims 16, 17, 20 and 21, wherein when P1 denotes a tirecircumferential-direction outermost end of the second lowland portionfurthest from the leading side edge or trailing side edge provided withthe second lowland portion in the tire circumferential direction and Lcdenotes a dimension measured along the tire circumferential directionfrom the tire circumferential-direction outermost end P1 to the leadingside edge or trailing side edge provided with the second lowlandportion, Lc is 2 mm to 25 mm.

The action of the pneumatic tire recited in claim 26 will next bedescribed.

By setting Lc to be 2 mm to 25 mm, it is possible to sufficiently reducethe noise level.

The invention recited in claim 27 is the pneumatic tire of any one ofclaims 16, 17, 20, 21 and 26, wherein when P1 denotes a tirecircumferential-direction outermost end of the second lowland portionfurthest from the leading side edge or trailing side edge provided withthe second lowland portion, Lc denotes a dimension measured along thetire circumferential direction from the tire circumferential-directionoutermost end P1 to the leading side edge or trailing side edge providedwith the second lowland portion, and A denotes a dimension of the endedge on the tire equatorial plane side measured along the tirecircumferential direction, Lc/A is 0.17 to 0.83.

The action of the pneumatic tire recited in claim 27 will next bedescribed.

By setting Lc/A to be 0.17 to 0.83, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 28 is the pneumatic tire of any one ofclaims 16, 17, 20, 21, 26 and 27, characterized in that, in the leadingside edge or trailing side edge of the block at the outermost side inthe tire widthwise direction provided with the second lowland portion,when Ld denotes a dimension measured along the tire widthwise directionfrom an end portion, of the block, on the tire equatorial plane side tothe second lowland, Ld is 3 mm to 15 mm.

The action of the pneumatic tire recited in claim 28 will next bedescribed.

By setting Ld to be 3 mm to 15 mm, it is possible to sufficiently reducethe noise level.

The invention recited in claim 29 is the pneumatic tire of any one ofclaims 16, 17, 20, 21, 26, 27 and 28, wherein in the leading side edgeor trailing side edge of the block at the outermost side in the tirewidthwise direction provided with the second lowland portion, when Lddenotes a dimension measured along the tire widthwise direction from anend portion, of the block, on the tire equatorial plane side to thesecond lowland and B denotes a dimension of the block at the outermostside in the tire widthwise direction measured, along the tire widthwisedirection, from the end edge on the tire equatorial plane side to theground-contact edge on the tire widthwise-direction outer side, Ld/B is0.15 to 0.75.

The action of the pneumatic tire recited in claim 29 will next bedescribed.

By setting Ld/B to be 0.15 to 0.75, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 30 is the pneumatic tire of any one ofclaims 16, 17, 20, 21, 26, 27, 28 and 29, wherein when P1 denotes a tirecircumferential-direction outermost end of the second lowland portionfurthest from the leading side edge or trailing side edge provided withthe second lowland portion, P2 denotes an intersection between theleading side edge or trailing side edge provided with the second lowlandportion and an imaginary straight line FL that passes through the tirecircumferential-direction outermost end P1 along the tirecircumferential direction, and Le denotes a dimension measured along thetire widthwise direction from the intersection P2 to the end portion onthe tire equatorial plane side of the second lowland portion, Le is 2 mmto 15 mm.

The action of the pneumatic tire recited in claim 30 will next bedescribed.

By setting Le to be 2 mm to 15 mm, it is possible to sufficiently reducethe noise level.

The invention recited in claim 31 is the pneumatic tire of any one ofclaims 16, 17, 20, 21, 26, 27, 28, 29 and 30, wherein when P1 denotes atire circumferential-direction outermost end of the second lowlandportion furthest from the leading side edge or trailing side edgeprovided with the second lowland portion, P2 denotes an intersectionbetween the leading side edge or trailing side edge provided with thesecond lowland portion and an imaginary straight line FL that passesthrough the tire circumferential-direction outermost end P1 along thetire circumferential direction, Le denotes a dimension measured alongthe tire widthwise direction from the intersection P2 to the end portionon the tire equatorial plane side of the second lowland portion, and Bdenotes a dimension of the block at the outermost side in the tirewidthwise direction measured, in the widthwise direction, from the endedge on the tire equatorial plane side to the ground-contact edge on thetire widthwise-direction outer side, Le/B is 0.1 to 0.75.

The action of the pneumatic tire recited in claim 31 will next bedescribed.

By setting Le/B to be 0.1 to 0.75, it is possible to sufficiently reducethe noise level.

The invention recited in claim 32 is the pneumatic tire of any one ofclaims 16, 17, 20, 21, 26, 27, 28, 29, 30 and 31, wherein when P1denotes a tire circumferential-direction outermost end of the secondlowland portion furthest from the leading side edge or trailing sideedge provided with the second lowland portion, P2 denotes anintersection between the leading side edge or trailing side edgeprovided with the second lowland portion and an imaginary straight lineFL that passes through the tire circumferential-direction outermost endP1 along the tire circumferential direction, and Lf denotes a dimensionmeasured along the tire widthwise direction from the intersection P2 tothe tire widthwise-direction outer side end of the second lowlandportion, Lf is 2 mm or greater.

The action of the pneumatic tire recited in claim 32 will next bedescribed.

By setting Lf to be 2 mm or greater, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 33 is the pneumatic tire of any one ofclaims 16, 17, 20, 21, 26, 27, 28, 29, 30, 31 and 32, wherein when P1denotes a tire circumferential-direction outermost end of the secondlowland portion furthest from the leading side edge or trailing sideedge provided with the second lowland portion, P2 denotes anintersection between the leading side edge or trailing side edgeprovided with the second lowland portion and an imaginary straight lineFL that passes through the tire circumferential-direction outermost endP1 along the tire circumferential direction, Lf denotes a dimensionmeasured along the tire widthwise direction from the intersection P2 tothe tire widthwise-direction outer side end of the second lowlandportion, and B denotes a dimension of the block at the outermost side inthe tire widthwise direction measured, in the tire widthwise direction,from the end edge on the tire equatorial plane side to theground-contact edge on the tire widthwise-direction outer side, Lf/B is0.1 or greater.

The action of the pneumatic tire recited in claim 33 will next bedescribed.

By setting Lf/B to be 0.1 or greater, it is possible to sufficientlyreduce the noise level.

The invention recited in claim 34 is the pneumatic tire of any one ofclaims 15 to 33, wherein when the block at the outermost side in thetire widthwise direction is viewed in cross section along the tirewidthwise direction, the highland portion and the lowland portion areprovided in any portion in the tire circumferential direction, in across-sectional view.

The action of the pneumatic tire recited in claim 34 will next bedescribed.

By setting the tread surface configuration so that the highland portionand the lowland portion are provided in any portion in the tirecircumferential direction when the block at the outermost side in thetire widthwise direction is viewed in cross section along the tirewidthwise direction, it is possible to make the input per unit time ofthe peak force resulting from deformation prolonged from the timecontact is initiated to the time when separation is completed. In thismanner, it is possible to suppress the level of noise generated by thetire widthwise-direction outermost side block at an even lower level.

The invention recited in claim 35 is the pneumatic tire of any one ofclaims 15 to 34, wherein in the block at the outermost side in the tirewidthwise direction, the highland portion includes a flat portion thatcoincides with a tire outer contour configuration.

The action of the pneumatic tire recited in claim 35 will next bedescribed.

Three-dimensionalization of the tread surface of the block significantlychanges ground-contact characteristics and changes the characteristicsof the block. When three-dimensionalization of the tread surface becomesexcessive, i.e., when there is no flat portion coinciding with the tireouter contour configuration on the tread surface, it becomes impossibleto reduce the noise level.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a block of a pneumatic tire relating toa first embodiment.

FIG. 2 is a plan view of a tread of the pneumatic tire relating to thefirst embodiment.

FIG. 3 is a cross sectional view of the block.

FIG. 4 is a perspective view of a block of a pneumatic tire relating toa third embodiment.

FIG. 5 is a perspective view of a block of a pneumatic tire relating toa fourth embodiment.

FIG. 6 is a perspective view of a block of a pneumatic tire relating toa fifth embodiment.

FIG. 7 is a plan view of a tread of a pneumatic tire relating to a sixthembodiment.

FIG. 8 is a perspective view of a block of the pneumatic tire relatingto the sixth embodiment.

FIG. 9 is a plan view of the block of the pneumatic tire relating to thesixth embodiment.

FIG. 10 is a perspective view of a block of a pneumatic tire ofConventional Example 1.

FIG. 11 is a perspective view of a block of a pneumatic tire ofConventional Example 2.

FIG. 12 is a perspective view of a block of a pneumatic tire of Example20.

FIG. 13 is a perspective view of a shoulder block of a pneumatic tirerelating to a seventh embodiment of the invention.

FIG. 14 is a plan view of a tread of the pneumatic tire relating to theseventh embodiment of the invention.

FIG. 15 is a cross sectional view along a tire widthwise direction ofthe shoulder block.

FIG. 16 is a cross view along the circumferential direction of theshoulder block.

FIG. 17 is a perspective view of a shoulder block of a pneumatic tirerelating to another embodiment of the invention.

FIG. 18 is a perspective view of a shoulder block of a pneumatic tirerelating to yet another embodiment of the invention.

FIG. 19 is a perspective view of a shoulder block of a pneumatic tirerelating to yet another embodiment of the invention.

FIG. 20 is a perspective view of a shoulder block of a pneumatic tirerelating to yet another embodiment of the invention.

FIGS. 21A and 21B are the results of Test Example 4.

FIGS. 22A and 22B are the results of Test Example 5.

FIGS. 23A and 23B are the results of Test Example 6.

FIGS. 24A and 24B are the results of Test Example 7.

FIGS. 25A and 25B are the results of Test Example 8.

FIGS. 26A and 26B are the results of Test Example 9.

FIGS. 27A and 27B are the results of Test Example 10.

FIGS. 28A and 28B are the results of Test Example 11.

FIG. 29A is a plan view of a tread of a pneumatic tire of Test Example12, and FIG. 29B is a plan view of a shoulder block of a tire of Example51.

FIG. 30 is a perspective view of a shoulder block of a pneumatic tirerelating to a conventional example.

FIG. 31 is a plan view of a tread of a pneumatic tire relating to yetanother embodiment of the invention.

FIG. 32 is an explanatory view illustrating ground-contacting pressureof the blocks shown in FIG. 31.

DETAILED DESCRIPTION OF THE EMBODIMENTS

First Embodiment

A first embodiment of the invention will be described in detail belowwith reference to the drawings.

As shown in FIG. 2, a plurality of rectangular blocks 18 are provided ona tread 12 of a pneumatic tire 10 by dividing the tread 12 by pluralcircumferential-direction grooves 14 that extend along a tirecircumferential direction (the direction of arrow A and the direction ofarrow B) and by plural lug grooves 16 that intersect thecircumferential-direction grooves 14 and extend along a tire widthwisedirection (the directions of arrow W).

It should be noted that the pneumatic tire 10 rotates in the directionof arrow A when the vehicle moves forward.

As shown in FIG. 1, a tread surface 20 of the blocks 18 includes a flatportion 22 (hatched portion in the drawing) that coincides with a tire(tread) outer contour configuration.

In FIG. 1, reference numeral 18A denotes a leading edge of the block 18,and reference numeral 18B denotes a trailing edge of the block 18. Whenthe pneumatic tire 10 rolls on a road surface, the block 18 contacts theroad surface initially by the leading edge 18A and separates from theroad surface lastly by the trailing edge 18B.

In the block 18 of the present embodiment, the height of the trailingedge 18B (measured from a groove bottom) is constant, but the height ofthe leading edge 18A differs in the tire widthwise direction.

A chamfered portion 24 is formed at a corner portion at a tirewidthwise-direction outer side (direction of arrow D side) of theleading edge 18A of the block 18 (it should be noted that the block 18shown in FIG. 1 is a block 18 positioned to the right side of a tireequatorial plane CL of FIG. 2).

As shown in FIG. 3, the chamfered portion 24 has a surface that curves(in the present embodiment, an arc having a curvature radius R) convexlytowards the tire outer side and smoothly connects with the flat portion22.

As shown in FIG. 1, a border 26 between the chamfered portion 24 and theflat portion 22 lies on a straight line that connects a point 28 locatedat the leading edge 18A and distanced by a dimension e from a tirewidthwise-direction outer-side end 18Aa of the leading edge 18A towardsthe tire equatorial plane (direction of arrow C), with a tirewidthwise-direction outer side end 18Ba of the trailing edge 18B. Theheight of the chamfered portion 24 gradually decreases from the border26 towards the tire widthwise-direction outer side end 18Aa of theleading edge 18A. Namely, the tire widthwise-direction outer side end18Aa of the leading edge 18A becomes the lowest portion of the leadingedge 18A.

Reference letter a in FIG. 1 denotes the dimension of the block 18 inthe tire widthwise direction (tire widthwise-direction lengths of theleading edge 18A and the trailing edge 18B, i.e., edges arranged in thecircumferential direction), reference letter b denotes the dimension ofthe block 18 in the tire circumferential direction (tirecircumferential-direction lengths of edges 40 and 48 arranged in thewidthwise-direction), reference letter h₀ denotes the height of theblock 18 (height of the flat portion 22), reference letter e denotes thetire widthwise-direction dimension of the chamfered portion 24 at theleading edge 18A, reference letter h₁ denotes the depth from the flatportion 22 (plane) to the lowest portion of the chamfered portion 24 (inthe present embodiment, the tire widthwise-direction outer side end18Aa), and reference letter c denotes the tire widthwise-directiondimension of the flat portion (highland portion) at the leading edge18A.

(Action)

The action of the pneumatic tire 10 of the present embodiment will nextbe described.

When the pneumatic tire 10 rolls and the blocks 18 contact the roadsurface, first, with respect to the leading edge 18A, the flat portion22 contacts the ground, and then the chamfered portion 24 contacts theground. Because the height of the chamfered portion 24 graduallydecreases towards the tire widthwise-direction outer side end, theleading edge 18A at the chamfered portion 24 gradually makes contactwith the road surface.

Namely, because all of the leading edge 18A of the block 18 does notmake immediate contact with the road surface but rather graduallycontacts the road surface, force input that generates sound is dispersedin terms of input timing and it is possible to suppress the generationof noise (mainly a striking sound) when the block 18 initially contactsthe road surface.

Furthermore, because the tire widthwise-direction dimension of the flatportion 22 changes in the tire circumferential direction, i.e., becausethe tire widthwise-direction position of the flat portion 22 changes inthe tire circumferential direction, it is possible for the entire blockto gently receive stress generated at the time of rolling, whereby it ispossible to suppress the level of noise generated by the block 18 at thetime the block 18 contacts the ground at a low level.

It should be noted that, when the tire widthwise-direction dimension cof the flat portion 22 at the leading edge 18A falls below 3 mm, itbecomes impossible to sufficiently reduce the noise level.

Additionally, when the tire widthwise-direction dimension c of the flatportion 22 at the leading edge 18A exceeds 15 mm, it becomes impossibleto sufficiently reduce the noise level.

Therefore, it is preferable to set the tire widthwise-directiondimension c of the flat portion 22 at the leading edge 18A to be 3 mm to15 mm.

Also, when the dimension c is less than 0.15 times the dimension a, itbecomes impossible to sufficiently reduce the noise level.

Additionally, when the dimension c is greater than 0.75 times thedimension a, it becomes impossible to sufficiently reduce the noiselevel.

Therefore, it is preferable to set the dimension c to be 0.15 to 0.75times the dimension a.

Also, when the depth h₁ is less than 0.1 mm, it becomes impossible tosufficiently reduce the noise level.

Additionally, when the depth h₁ exceeds 2.5 mm, it becomes impossible tosufficiently reduce the noise level.

Therefore, it is preferable to set the depth h₁ to be 0.1 mm to 2.5 mm.

Also, with respect to the leading edge 18A, when the depth h₁ is lessthan 0.01 times the height h₀ of the flat portion 22, it becomesimpossible to sufficiently reduce the noise level.

Additionally, when the depth h₁ is greater than 0.25 times the height hoof the flat portion 22, it becomes impossible to sufficiently reduce thenoise level.

Also, when the tire widthwise-direction dimension e of the chamferedportion 24 at the leading edge 18A is less than 5 mm, it becomesimpossible to sufficiently reduce the noise level.

Additionally, when the dimension e exceeds 17 mm, it becomes impossibleto sufficiently reduce the noise level.

Also, when the dimension e is less than 0.25 times the dimension a, itbecomes impossible to sufficiently reduce the noise level.

Additionally, when the dimension e is greater than 0.85 times thedimension a, it becomes impossible to sufficiently reduce the noiselevel.

Second Embodiment

A second embodiment of the invention will next be described in detail.It should be noted that the same reference numerals will be given tostructures that are the same as those in the preceding embodiment andthat description of those structures will be omitted.

The present embodiment is an example in which the pneumatic tire 10 ofthe first embodiment is reversed when put on a vehicle (i.e., thedirection of arrow B in FIG. 1 is the direction in which the tirerotates when the vehicle moves forward).

Namely, in the second embodiment, the portion that was the leading edge18A in the first embodiment becomes the trailing edge, and the portionthat was the trailing edge 18B in the first embodiment becomes theleading edge.

In the present embodiment, when the trailing edge of the block 18separates from the road surface, the chamfered portion 24 of thetrailing edge separates from the road surface at first, and then theflat portion 22 of the trailing edge separates from the road surface.

That is, the trailing edge does not separate from the road surface allat once but gradually. Therefore, it is possible to suppress the noiselevel when the block 18 separates from the road surface at a low level.

Third Embodiment

A third embodiment of the invention will next be described in detail. Itshould be noted that the same reference numerals will be given tostructures that are the same as those in the preceding embodiments andthat description of those structures will be omitted.

As shown in FIG. 4, in the block 18 of the present embodiment, achamfered portion 30 that is the same as the chamfered portion 24 isformed at the tire equatorial plane side (direction of arrow C side) ofthe trailing edge 18B.

A border 32 between the chamfered portion 30 and the flat portion 22lies on a straight line that connects a point 34 located at the trailingedge 18B and distanced by a dimension e′ from a tire equatorial planeside end 18Bb of the trailing edge 18B towards the tirewidthwise-direction outer side, with a tire equatorial plane side end18Ab of the leading edge 18A. The height of the chamfered portion 30gradually decreases from the border 32 towards the tire equatorial planeside end 18Bb of the trailing edge 18B. Namely, the tire equatorialplane side end 18Bb of the trailing edge 18B becomes the lowest portionof the trailing edge 18B.

Namely, in the present embodiment, the chamfered portion structure ofthe first embodiment is combined with the chamfered portion structure ofthe second embodiment, and it is possible to suppress both the level ofnoise generated when the blocks 18 contact the road surface and thelevel of noise generated when the blocks 18 separate from the roadsurface at low levels, whereby the noise level of the tire can besuppressed even more lowly.

Fourth Embodiment

A fourth embodiment of the invention will next be described in detail.It should be noted that the same reference numerals will be given tostructures that are the same as those in the preceding embodiments andthat description of those structures will be omitted.

As shown in FIG. 5, in the block 18 of the present embodiment, achamfered portion 36 is formed at the tire widthwise-direction outerside of the leading edge 18A, a chamfered portion 38 is formed at thetire widthwise-direction outer side of the trailing edge 18B, and achamfered portion 42 is formed at the tire equatorial plane side edge40, whereby the entire flat portion 22 curves in a substantiallycircular arc.

It should be noted that the tire widthwise-direction outer side end 18Aaof the leading edge 18A is the lowest portion of the chamfered portion36, and that the height of the chamfered portion 36 gradually decreasesfrom a border 37 between the flat portion 22 and the chamfered portion36 towards the tire widthwise direction outer side end 18Aa.

Similarly, the tire widthwise-direction outer side end 18Ba of thetrailing edge 18B is the lowest portion of the chamfered portion 38, andthe height of the chamfered portion 38 gradually decreases from a border39 between the flat portion 22 and the chamfered portion 38 towards thetire widthwise-direction outer side end 18Bb.

Also, the longitudinal-direction center portion of the tire equatorialplane side edge 40 is the lowest portion of the chamfered portion 42,and the height of the chamfered portion 42 gradually decreases from aborder 43 between the flat portion 22 and the chamfered portion 42towards the longitudinal-direction center of the edge 40.

In the present embodiment also, it is possible to suppress both thelevel of noise generated when the blocks 18 contact the road surface andthe level of noise generated when the blocks 18 separate from the roadsurface at low levels, whereby the noise level of the tire can besuppressed even more lowly.

Fifth Embodiment

A fifth embodiment of the invention will next be described in detail. Itshould be noted that the same reference numerals will be given tostructures that are the same as those in the preceding embodiments andthat description of those structures will be omitted.

As shown in FIG. 6, in the block 18 of the present embodiment, achamfered portion 44 is formed at the tire widthwise-direction outerside of the leading edge 18A, a chamfered portion 46 is formed at thetire equatorial plane outer side of the trailing edge 18B, a chamferedportion 50 is formed at the trailing edge 18B side of the tirewidthwise-direction outer side edge 48, and a chamfered portion 52 isformed at a leading edge 18A side of the tire equatorial plane side edge40, whereby the entire flat portion 22 curves in a substantial S-shape.

It should be noted that the tire widthwise-direction outer side end 18Aaof the leading edge 18A is the lowest portion of the chamfered portion44, and that the height of the chamfered portion 44 gradually decreasesfrom a border 45 between the flat portion 22 and the chamfered portion44 towards the tire widthwise-direction outer side end 18Aa.

The tire equatorial plane side end 18Bb of the trailing edge 18B is thelowest portion of the chamfered portion 46, and the height of thechamfered portion 46 gradually decreases from a border 47 between theflat portion 22 and the chamfered portion 46 towards the tirewidthwise-direction outer side end 18Bb.

The circumferential-direction center portion of the chamfered portion 50is the lowest portion of the chamfered portion 50 at the tirewidthwise-direction outer side edge 48, and the height of the chamferedportion 50 gradually decreases from a border 51 between the flat portion22 and the chamfered portion 50 towards the circumferential-directioncenter of the chamfered portion 50 of the edge 48.

Also, the circumferential-direction center portion of the chamferedportion 52 is the lowest portion of the chamfered portion 52 provided atthe tire equatorial plane side edge 40, and the height of the chamferedportion 52 gradually decreases from a border 53 between the flat portion22 and the chamfered portion 52 towards the circumferential-directioncenter of the chamfered portion 52 of the edge 40.

In the present embodiment also, it is possible to suppress both thelevel of noise generated when the blocks 18 contact the road surface andthe level of noise generated when the blocks 18 separate from the roadsurface at low levels, whereby the noise level of the tire can besuppressed even more lowly.

Sixth Embodiment

A sixth embodiment of the invention will next be described in detail. Itshould be noted that the same reference numerals will be given tostructures that are the same as those in the preceding embodiments andthat description of those structures will be omitted.

As shown in FIG. 7, a rib 58 is provided on the tire equatorial planeCL, and parallelogrammatic blocks 60 are provided at both sides of therib 58, by dividing the tread 12 of the pneumatic tire 10 by pluralcircumferential-direction grooves 54 that extend along the tirecircumferential direction (the direction of arrow A and the direction ofarrow B) and by plural slanted grooves 56 that extend in the tirewidthwise direction from the circumferential-direction grooves 54 andslant with respect to the tire widthwise direction.

It should be noted that the pneumatic tire 10 rotates in the directionof arrow A when the vehicle moves forward.

As shown in FIGS. 8 and 9, a tread surface 62 of the block 60 includes aflat portion (hatched portion in the drawings) 64 that coincides with atire outer contour configuration.

In the drawings, reference numeral 60A denotes a leading edge of theblock 60, and reference numeral 60B denotes a trailing edge of the block60. When the pneumatic tire 10 rolls on a road surface, the block 60contacts the road surface initially by the leading edge 60A andseparates from the road surface lastly by the trailing edge 60B.

In the block 60 of the present embodiment, each of the height of thetrailing edge 60B and the height of the leading edge 60A differs in thetire widthwise direction.

A chamfered portion 66 is formed at a corner portion at the tirewidthwise-direction outer side (direction of arrow D side) of theleading edge 60A, and a chamfered portion 68 is formed at a cornerportion at the tire equatorial plane side of the trailing edge 60B.

The chamfered portion 66 and the chamfered portion 68 are curvedsurfaces that smoothly connect with the flat portion 64.

A border 70 between the chamfered portion 66 and the flat portion 64lies on a straight line that connects a point 72 located at the leadingedge 60A and distanced by a dimension c from a tire equatorial planeside end 60Ab of the leading edge 60A towards the tire widthwisedirection outer side, with a tire widthwise-direction outer side end60Ba of the trailing edge 18B. The height of the chamfered portion 66gradually decreases from the border 70 towards a tirewidthwise-direction outer side end 60Aa of the leading edge 60A. Namely,the tire widthwise-direction outer side end 60Aa of the leading edge 60Abecomes the lowest portion of the leading edge 60A.

A border 74 between the chamfered portion 68 and the flat portion 64lies on a straight line that connects a point 76 located at the trailingedge 60B and distanced by a dimension c′ from a tire widthwise directionouter side end 60Ba of the trailing edge 60B towards the tire equatorialplane side, with a tire equatorial plane side end 60Ab of the leadingedge 60A. The height of the chamfered portion 68 gradually decreasesfrom the border 74 towards a tire equatorial plane side end 60Bb of thetrailing edge 60B. Namely, the tire equatorial plane side end 60Bb ofthe trailing edge 60B becomes the lowest portion of the trailing edge60B.

In FIGS. 8 and 9, reference letter a denotes the dimension of the block60 in the tire widthwise direction (i.e., tire widthwise-directiondimension of the leading edge 60A and the trailing edge 60B), referenceletter b denotes the circumferential direction dimension of edges 78 and80 of the block 60 arranged in the tire widthwise direction, referenceletter h₀ denotes the height of the block 60, reference letter e denotesthe tire widthwise-direction length of the chamfered portion 66 at theleading edge 60A, reference letter h₁ denotes the depth from the flatportion 64 (plane) to the lowest portion of the chamfered portion 66 (inthe present embodiment, the tire widthwise-direction outer side end60Aa), reference letter c denotes the tire widthwise-direction dimensionof the flat portion (highland portion) at the leading edge 60A,reference letter e′ denotes the tire widthwise-direction length of thechamfered portion 68 at the trailing edge 60B, reference letter h₂denotes the depth from the flat portion 64 (plane) to the lowest portionof the chamfered portion 68 (in the present embodiment, the tireequatorial plane side end 60Bb), reference letter c′ denotes the tirewidthwise-direction dimension of the flat portion (highland portion) atthe trailing edge 60B, and angle θ denotes the angle of the slantedgrooves 56 with respect to the tire widthwise direction.

In the present embodiment also, the leading edge 60A of the block 60gradually makes contact with the ground, and the trailing edge 60B ofthe block 60 gradually separates from the road surface. Furthermore,because the position of the flat portion 64 changes in the tirewidthwise direction, it is possible to suppress the level of noisegenerated by the block 18 at a low level.

TEST EXAMPLE 1

First, three types of pneumatic tires for conventional example wereprepared, and noise was measured using an indoor drum tester. The testmeasured sound pressure (peaks of sound pressure waveforms) in thevicinity of the sides of the test tires at a speed of 80 km/hour.

Tire of Conventional Example 1: a tire including a tread provided withrectangular blocks in which the tread surface was flat (along the tireouter contour configuration) and having no chamfered portions formedthereon. The tread pattern was the same as the pattern of FIG. 2. Withrespect to the three rows of blocks at the center, the dimension b was30 mm, the dimension a was 20 mm, and the height h₀ was 10 mm. Withrespect to the shoulder blocks, the dimension b was 30 mm, the dimensiona was 50 mm, and the height h₀ was 10 mm.

Tire of Conventional Example 2: a tire including a tread provided with,as shown in FIG. 10, blocks 102 in which the tirecircumferential-direction center portion thereof was flat (hatchedportion) and the tire circumferential-direction sides (leading edge andtrailing edge) thereof were chamfered as chamfered portions 100. Withrespect to the chamfered portions 100, the length in the circumferentialdirection was 10 mm and the depth h₁ was 0.5 mm. The tread pattern andthe outer shape dimension of the blocks 100 were the same as inConventional Example 1.

Tire of Conventional Example 3: a tire including a tread provided with,as shown in FIG. 11, blocks 106 in which the tirecircumferential-direction center portion thereof was flat (hatchedportion) and the tire widthwise-direction sides thereof were chamferedas chamfered portions 104. With respect to the chamfered portions 104,the length i in the tire widthwise direction was 6 mm and the depth h₁was 0.5 mm. The tread pattern and the outer shape dimension of theblocks 106 were the same as in Conventional Example 1.

The sizes of the test tires were all 195/65R14.

Evaluation was conducted using an index display in which the size of thesound pressure waveform peak of the pneumatic tire of ConventionalExample 1 was set at 100. The smaller the numerical value, the lower wasthe noise level, indicating that the amount of noise generated wassuppressed at a low level. TABLE 1 Noise Level Index ConventionalExample 1 100 Conventional Example 2 115 Conventional Example 3 103

It will be understood from the test results that simply disposingchamfered portions at the blocks as in Conventional Examples 2 and 3only resulted in increasing noise.

TEST EXAMPLE 2

In order to verify the effects of the invention, the pneumatic tire ofConventional Example 1 and a pneumatic tire of Example 1, to which theinvention was applied, were prepared. A test was conducted in the samemanner as in Test Example 1, and noise was evaluated.

Pneumatic tire of Example 1: the pneumatic tire of the preceding firstembodiment, with the outer shape dimension of the blocks being the sameas that of Conventional Example 1. The tire widthwise-direction length eof the chamfered portion in the leading edge was 17 mm in the three rowsof blocks in the center and 17 mm in the shoulder blocks. The depth h₁of the chamfered portion was 0.5 mm.

The sizes of the test tires were both 195/65R14. TABLE 2 Noise LevelIndex Conventional Example 1 100 Example 1 94

It will be understood from the results of the test that noise level wassuppressed more lowly in the pneumatic tire of Example 1, to which theinvention was applied, than in the pneumatic tire of ConventionalExample 1.

TEST EXAMPLE 3

In order to verify the effects of the invention, the pneumatic tire ofthe conventional example 1 and a pneumatic tire of Example 2, to whichthe invention was applied, were prepared. A test was conducted in thesame manner as in Test Example 1, and noise was evaluated.

Pneumatic tire of Example 2: the pneumatic tire of the preceding secondembodiment. The outer shape dimension of the blocks was the same as thatof Conventional Example 1. The tire widthwise-direction length e of thechamfered portion in the trailing edge was 17 mm in the three rows ofblocks in the center and 17 mm in the shoulder blocks. The depth h₁ ofthe chamfered portion was 0.5 mm.

The sizes of the test tires were both 195/65R14. TABLE 3 Noise LevelIndex Conventional Example 1 100 Example 2 93

It will be understood from the results of the test that noise level wassuppressed more lowly in the pneumatic tire of Example 2, to which theinvention was applied, than in the pneumatic tire of ConventionalExample 1.

TEST EXAMPLE 4

In order to verify the effects of the invention, the pneumatic tire ofthe conventional example 1 and a pneumatic tire of Example 3, to whichthe invention was applied, were prepared. A test was conducted in thesame manner as in Test Example 1, and noise was evaluated.

Pneumatic tire of Example 3: the pneumatic tire of the preceding thirdembodiment. The outer shape dimension of the blocks was the same as thatof Conventional Example 1, and the dimensions of the chamfered portionswere the same as those in Examples 1 and 2.

The sizes of the test tires were both 195/65R14. TABLE 4 Noise LevelIndex Conventional Example 1 100 Example 3 91

It will be understood from the results of the test that noise level wassuppressed more lowly in the pneumatic tire of Example 3, to which theinvention was applied, than in the pneumatic tire of ConventionalExample 1. Moreover, noise level was suppressed more lowly in thepneumatic tire of Example 3 than in the pneumatic tires of Examples 1and 2.

TEST EXAMPLE 5

In order to verify the effects of the invention, the pneumatic tire ofthe conventional example 1 and pneumatic tires of Examples 4 to 8, towhich the invention was applied, were prepared. A test was conducted inthe same manner as in Test Example 1, and noise was evaluated.

Pneumatic tires of Examples 4 to 8: as shown in FIG. 12, a chamferedportion was provided at each of the leading edge and the trailing edge,and the circumferential-direction length f of the flat portion at thetire equatorial plane side edge and at the tire widthwise-directionouter side edge was varied as shown in Table 5 below.

The pattern and outer shape dimension of the blocks were the same asthose in Conventional Example 1. Also, the tire widthwise-directionlength e of the chamfered portion 24 at the leading edge 18A was 17 mmin the three rows of blocks in the center and 17 mm in the shoulderblocks. The depth h₁ of the chamfered portion 24 was 0.5 mm.

Moreover, the tire widthwise-direction length e′ of the chamferedportion 30 at the trailing edge 18B was 17 mm in the three rows ofblocks in the center and 17 mm in the shoulder blocks. The depth h₂ ofthe chamfered portion 30 was 0.5 mm.

The sizes of the test tires were all 195/65R14. TABLE 5 f (mm) NoiseLevel Index Example 4 0 91 Example 5 10 93 Example 6 15 94 Example 7 2096 Example 8 25 98 Conventional Example 1 30 100

As the test results indicate, the shorter the value of thecircumferential-direction length f of the flat portion at the tireequatorial plane side edge and at the tire widthwise-direction outerside edge, the better were the results that were obtained.

TEST EXAMPLE 6

In order to verify the effects of the invention, the pneumatic tire ofthe conventional example 1 and pneumatic tires of Examples 9 and 10, towhich the invention was applied, were prepared. A test was conducted inthe same manner as in Test Example 1, and noise was evaluated. Thepneumatic tire of Example 9 was the pneumatic tire of the precedingfourth embodiment (see FIG. 5), and the pneumatic tire of Example 10 wasthe pneumatic tire of the preceding fifth embodiment (see FIG. 6).

Pneumatic tire of Example 9 (see FIG. 5): the depth h₁ of the chamferedportion 36 was 0.5 mm, the circumferential-direction length j of thechamfered portion 36 at the tire widthwise-direction outer side edge 48was 15 mm, the depth h₂ of the chamfered portion 38 was 0.5 mm, thecircumferential-direction length k of the chamfered portion 38 at thetire widthwise-direction outer side edge 48 was 15 mm, and the depth h₃of the chamfered portion 42 was 0.5 mm.

The dimension in the tire widthwise direction of the flat portion 22 was3 mm (constant) in the three rows of blocks in the center and 3 mm(constant) in the shoulder blocks.

Pneumatic tire of Example 10 (see FIG. 6): the depth h₁ of the chamferedportion 44 was 0.5 mm, the circumferential-direction length m of thechamfered portion 44 at the tire widthwise-direction outer side edge 48was 10 mm, the depth h₂ of the chamfered portion 46 was 0.5 mm, thecircumferential-direction length n of the chamfered portion 46 at thetire equatorial plane side edge 40 was 10 mm, thecircumferential-direction length o of the chamfered portion 50 at thetire widthwise-direction outer side edge 48 was 20 mm, thecircumferential-direction length q of the chamfered portion 52 at thetire equatorial plane side edge 40 was 20 mm, the depth h₃ of thechamfered portion 50 was 0.5 mm, and the depth h₄ of the chamferedportion 52 was 0.5 mm. The dimension in the tire widthwise direction ofthe flat portion 22 was 3 mm (constant) in the three rows of blocks inthe center and 3 mm (constant) in the shoulder blocks.

The sizes of the test tires were all 195/65R14. TABLE 6 Noise LevelIndex Conventional Example 1 100 Example 9 91 Example 10 93

It will be understood from the results of the test that noise level wassuppressed more lowly in the pneumatic tires of Examples 9 and 10, towhich the invention was applied, than in the pneumatic tire ofConventional Example 1.

TEST EXAMPLE 7

In order to verify the effects of the invention, the pneumatic tire ofConventional Example 1 and pneumatic tires of Examples 11 to 15, towhich the invention was applied, were prepared. A test was conducted inthe same manner as in Test Example 1, and noise was evaluated. Thepneumatic tires of Examples 11 to 15 were, as shown in FIG. 1, pneumatictires provided with the chamfered portion 24 at the tirewidthwise-direction outer side end side of the leading edge 18A of theblock 18, but the tire widthwise-direction dimension c of the flatportion 22 at the leading edge 18A was, as shown in Table 7 below,different.

The sizes of the test tires were all 195/65R14. TABLE 7 c (mm) NoiseLevel Index Conventional Example 1 100 Example 11 0 97 Example 12 3 91Example 13 10 92 Example 14 15 94 Example 15 16 97

It will be understood from the results of the test that, by setting thelength of the flat portion 22 in the leading edge 18A to be 3 to 15 mm,it was possible to reduce noise level.

The following Table 8 shows the relation between a ratio c/a and noiselevel, wherein “a” being the dimension a in the tire widthwise directionof the leading edge 18A of the block and “c” being the tirewidthwise-direction dimension c of the flat portion at the leading edge.

The sizes of the test tires were all 195/65R14. TABLE 8 c/a Noise LevelIndex Conventional Example 1 100 Example 11 0 97 Example 12 0.15 91Example 13 0.5 92 Example 14 0.75 94 Example 15 0.8 97

It will be understood from the results shown in Table 8 that, by settingthe length c of the flat portion 22 in the leading edge 18A to be 0.15to 0.75 times the tire widthwise-direction dimension a of the leadingedge, it was possible to reduce noise level.

The following Table 9 shows the relation between the tirewidthwise-direction length e of the chamfered portion 24 at the leadingedge 18A and noise level.

The sizes of the test tires were all 195/65R14. TABLE 9 e (mm) NoiseLevel Index Conventional Example 1 100 Example 11 20 97 Example 12 17 91Example 13 10 92 Example 14 5 94 Example 15 4 97

It will be understood from the results shown in Table 9 that, by settingthe tire widthwise-direction length e of the chamfered portion 24 at theleading edge 18A to be 5 to 17 mm, it was possible to reduce noiselevel.

The following Table 10 shows the relation between a ratio e/a and noiselevel, wherein “a” being the dimension a in the tire widthwise directionof the leading edge 18A of the block and “e” being the tirewidthwise-direction dimension e of the chamfered portion 24 at theleading edge 18A.

The sizes of the test tires were all 195/65R14. TABLE 10 e/a Noise LevelIndex Conventional Example 1 100 Example 11 1 97 Example 12 0.85 91Example 13 0.5 92 Example 14 0.25 94 Example 15 0.2 97

It will be understood from the results shown in Table 10 that, bysetting the ratio e/a to be 0.25 to 0.85, it was possible to reducenoise level.

TEST EXAMPLE 8

In order to verify the effects of the invention, the pneumatic tire ofConventional Example 1, pneumatic tires of Examples 16 to 20, to whichthe invention was applied, and a pneumatic tire of Comparative Example 1were prepared. A test was conducted in the same manner as in TestExample 1, and noise was evaluated. The pneumatic tires of Examples 16to 20 and the pneumatic tire of Comparative Example 1 were, as shown inFIG. 1, pneumatic tires provided with the chamfered portion 24 at thetire widthwise-direction outer side end side of the leading edge 18A ofthe block 18, but the depth h₁ of the chamfered portion of each tirewas, as shown in Table 7 below, different.

The sizes of the test tires were all 195/65R14. TABLE 11 h₁ (mm) NoiseLevel Index Conventional Example 1 100 Example 16 0.1 95 Example 17 0.591 Example 18 1.2 94 Example 19 2.5 95 Comparative Example 1 2.8 103

It will be understood from the results of the test that, by setting thedepth h₁ of the chamfered portion 24 to be 0.1 to 2.5 mm, it waspossible to reduce noise level.

The following Table 12 below shows the relation between a ratio h₁/h₀and noise level.

The sizes of the test tires were all 195/65R14. TABLE 12 h₁/h₀ NoiseLevel Index Conventional Example 1 100 Example 16 0.01 95 Example 170.05 91 Example 18 0.12 94 Example 19 0.25 95 Comparative Example 1 0.28103

It will be understood from the results shown in Table 12 that, bysetting the ratio h₁/h₀ to be 0.01 to 0.25, it was possible to reducenoise level.

TEST EXAMPLE 9

In order to verify the effects of the invention, a pneumatic tire ofConventional Example 4 and a pneumatic tire of Example 20, to which theinvention was applied, were prepared. A test was conducted in the samemanner as in Test Example 1, and noise was evaluated.

Embodiment 20: it was a pneumatic tire having a directional patternprovided with parallelogrammatic blocks as shown in FIG. 7, andchamfered portions 66 and 68 were provided as shown in FIGS. 8 and 9.

The width of the rib 58 was 10 mm, the groove width of thecircumferential-direction grooves 54 was 8 mm, and the groove width ofthe slanted grooves 56 was 7 mm.

With respect to the blocks 60 at the rib 58 sides, the tirewidthwise-direction dimension a was 25 mm, the tirecircumferential-direction dimension b of the edges arranged in the tirewidthwise-direction was 30 mm, the height h₀ was 10 mm, the depths h₁and h₂ were 0.5 mm, the angle θ was 40 degrees, and the tirewidthwise-direction dimension c of the flat portion 64 was 3 mm.

The dimensions of the blocks 60 at the shoulders were the same as thoseof the blocks 60 at the rib 58 sides.

Conventional Example 4: included the same pattern as the pneumatic tireof Example 20, but included blocks on which chamfered portions were notformed.

The sizes of the test tires were both 195/65R14. TABLE 13 Noise LevelIndex Conventional Example 4 100 Example 20 90

It will be understood from the test results that noise level was reducedmore in the pneumatic tire of Example 20, to which the invention wasapplied, than in the pneumatic tire of Conventional Example 4.

Seventh Embodiment

A seventh embodiment of the invention will next be described in detailwith reference to the drawings.

As shown in FIG. 14, plural rectangular center blocks 18 a, secondblocks 18 b, and shoulder blocks 18 c are provided on the tread 12 ofthe pneumatic tire 10, respectively, by dividing the tread 12 by pluralcircumferential-direction grooves 14 that extend along the tirecircumferential direction (the direction of arrow A and the directionopposite from the direction of arrow A) and by plural lug grooves 16that extend along the tire widthwise direction (the direction of arrow Rand the direction of arrow L) and intersect thecircumferential-direction grooves 14.

It should be noted that the pneumatic tire 10 rotates in the directionof arrow A when the vehicle moves forward.

As shown in FIG. 13, a tread surface of the shoulder blocks 18 cincludes the flat portion 22 that coincides with a tire (tread) outercontour configuration.

In FIG. 13, reference numeral 18E denotes a ground-contact end,reference numeral 18A denotes a leading edge of the shoulder block 18 c,and reference numeral 18B denotes a trailing edge of the shoulder block18 c. When the pneumatic tire 10 rolls on a road surface, the shoulderblock 18 c contacts the road surface at first by the leading edge 18Aand separates from the road surface at first by the trailing edge 18B.

A first chamfered portion 24 is formed at a corner portion at the tireequatorial plane side of the leading edge 18A of the shoulder block 18 c(it should be noted that the shoulder block 18 c shown in FIG. 13 is ashoulder block 18 c positioned to the right side of the tire equatorialplane CL of FIG. 14).

As shown in FIG. 15, the first chamfered portion 24 is a convex curvedsurface (in the present embodiment, a circular arc curved surface) thatsmoothly connects with the flat portion 22.

As shown in FIG. 13, a border 26 between the first chamfered portion 24and the flat portion 22 is diagonal with respect to the tirecircumferential direction, and the height of the first chamfered portion24 gradually decreases from the border 26 towards a tire equatorialplane side end 18Aa of the leading edge 18A.

Namely, the tire equatorial plane side end 18Aa of the leading edge 18Abecomes the lowest portion of the leading edge 18A within aground-contact surface.

A second chamfered portion 28 is formed at an intermediate portion ofthe trailing edge 18B of the shoulder block 18 c.

As shown in FIG. 16, the second chamfered portion 28 has a convex curvedsurface (in the present embodiment, a circular arc curved surface) thatsmoothly connects with the flat portion 22.

As shown in FIG. 13, a border 30 between the second chamfered portion 28and the flat portion 22 has a substantially circular arc configuration,and the height of the second chamfered portion 28 gradually decreasesfrom the border 30 towards a circular arc center of border 30.

Reference letter A denotes the dimension measured along the tirecircumferential direction of the end edge 18D on the tire equatorialplane side, reference letter B denotes the dimension measured, in thetire widthwise-outer-side direction, from the end edge 18D on the tireequatorial plane side of the shoulder block 18 c to the ground-contactend 18E, reference letter C denotes block height at the end edge 18D onthe tire equatorial plane side of the shoulder block 18 c, referenceletter Ha denotes the depth at the lowest portion of the first chamferedportion 24 (in the present embodiment, the tire equatorial plane sideend 18Aa) from the flat portion 22 (plane), reference letter La denotesthe dimension of the first chamfered portion 24 measured from the endedge 18D on the tire equatorial plane side 24 towards the tirewidthwise-direction outer side, reference letter Lb denotes thedimension of the first chamfered portion 24 measured along the tirecircumferential direction from the leading edge 18A, reference letter Hbdenotes the depth at the lowest portion of the second chamfered portion28 from the flat portion 22 (plane), reference letter P1 denotes thetire circumferential-direction outermost end of the second chamferedportion 28 that is furthest from the leading edge 18A (trailing edge18B) in the tire circumferential direction, reference letter Lc denotesthe dimension measured along the tire circumferential direction from thetire circumferential-direction outermost end P1 to the trailing edge18B, reference letter Ld is the dimension measured along the tirewidthwise direction from an end portion, of the block, on the tireequatorial plane side, of the trailing edge 18B to the second chamferedportion 28, P2 is an intersection between the trailing edge 18B and animaginary straight line FL that passes through the tirecircumferential-direction outermost end P1 along the tirecircumferential direction, reference letter Le is the dimension measuredalong the tire widthwise direction from the intersection P2 to a tireequatorial plane side end portion of the second chamfered portion 28,and reference letter Lf is the dimension measured along the tirewidthwise direction from the intersection P2 to the tirewidthwise-direction outer side end of the second chamfered portion 28.

Preferable ranges of each dimension and ratios will next be described.

Dimension Ha is preferably 0.2 mm to 2.5 mm.

Ratio Ha/C is preferably 0.02 to 0.25.

Dimension Hb is preferably 0.2 mm to 2.5 mm.

Ratio Hb/C is preferably 0.02 to 0.25.

Dimension La is preferably 5 mm or greater.

Ratio La/B is preferably 0.25 or greater.

Dimension Lb is preferably 10 mm or greater.

Ratio Lb/A is preferably 0.3 or greater.

Dimension Lc is preferably 2 mm to 25 mm.

Ratio Lc/A is preferably 0.17 to 0.83.

Dimension Ld is preferably 3 mm to 15 mm.

Ratio Ld/B is preferably 0.15 to 0.75.

Ratio Le is preferably 2 mm to 15 mm.

Ratio Le/B is preferably 0.1 to 0.75.

Dimension Lf is preferably 2 mm or greater.

Ratio Lf/B is preferably 0.1 or greater.

(Action)

The action of the pneumatic tire 10 of the present embodiment will nextbe described.

When the pneumatic tire 10 rolls and the shoulder blocks 18 c contactthe road surface, first, with respect to the leading edge 18A, the flatportion 22 contacts the ground, and then the first chamfered portion 24contacts the ground.

Because the height of the first chamfered portion 24 gradually decreasestowards the tire equatorial plane side, the first chamfered portion 24gradually makes contact with the road surface.

Namely, because all of the leading edge 18A of the shoulder block 18 cdoes not make immediate contact with the road surface but rathergradually contacts the road surface, force input that generates sound isdispersed in terms of input timing and it is possible to suppress thegeneration of noise (mainly a striking sound) at the initial stage ofthe shoulder block 18 c contacting the road surface.

Furthermore, because the tire widthwise-direction dimension of the flatportion 22 changes in the tire circumferential direction, i.e., becausethe tire widthwise-direction position of the flat portion 22 changes inthe tire circumferential direction, it is possible for the entire blockto gently receive stress generated at the time of rolling, whereby it ispossible to suppress the level of noise generated by the shoulder block18 c at the time the shoulder block 18 c contacts the ground at a lowlevel.

Moreover, because the second chamfered portion 28 is formed at thetrailing edge 18B side on the shoulder block 18 c, the trailing edge 18Bof the shoulder block 18 c does not separate from the road surface allat once but gradually. Therefore, it is possible to suppress thegeneration of noise when the shoulder block 18 c separates from the roadsurface.

When the dimension Ha, the ratio Ha/C, the dimension Hb, the ratio Hb/C,the dimension La, the ratio La/B, the dimension Lb, the ratio Lb/A, thedimension Lc, the ratio Lc/A, the dimension Ld, the ratio Ld/B, thedimension Le, the ratio Le/B, the dimension Lf, and the ratio Lf/B falloutside of the aforementioned ranges, it becomes impossible tosufficiently suppress the generation of noise.

It should be noted that, although the second chamfered portion 28 isdisposed closer to the tire equatorial plane side than to theground-contact end 18E in FIG. 13, the second chamfered portion 28 mayalso be disposed such that a portion thereof extends to the tirewidthwise-direction outer side beyond the ground-contact end 18E, asshown in FIG. 17.

Also, it is preferable that the flat portion 22 and at least one of thefirst chamfered portion 24 and the second chamfered portion 28 areprovided in any portion in the tire circumferential direction when theshoulder block 18 c is seen in cross section along the tire widthwisedirection.

By the aforementioned structure, it is possible to make the input perunit time of the peak force resulting from deformation prolonged for aperiod from leading initiation to trailing completion. In this manner,it is possible to suppress the level of noise generated by the shoulderblock 18 c at an even lower level.

In the shoulder block 18 c, by making the ground-contact edge 18E theflat portion 22 along the tire outer contour, it becomes possible tomaximize the vertical interval of the ground-contact portion at theleading edge and to delay the time that the end thereof contacts theground as late as possible.

As shown in FIG. 18, it is preferable to dispose chamfered portions 32,which are the same as the first chamfered portion 24, at oppositecorners at the leading side and at the trailing side in the centerblocks 18 a and in the second blocks 18 b.

In such a structure, similar to the shoulder blocks 18 c, it is alsopossible to suppress in the center blocks 18 a and in the second blocks18 b the level of noise generated by the blocks at a low level.

Another Embodiment

Although the first chamfered portion 24 and the second chamfered portion28 were disposed on the shoulder block 18 c in the preceding embodiment,the present invention is not limited to the same. While the effects maydrop somewhat, it is also possible to provide only the first chamferedportion 24 on the shoulder block 18 c, as shown in FIG. 19, or toprovide only the second chamfered portion 28 on the shoulder block 18 c,as shown in FIG. 20.

Also, although the pneumatic tire 10 in the preceding embodiment rolledin the direction of arrow A, the same effects can be obtained when thepneumatic tire 10 rolls in the direction opposite from the direction ofarrow A.

Although the lug grooves 16 extended in the tire widthwise direction inthe pneumatic tire 10 of the preceding embodiment, the lug grooves 16may also slant (angle θ) with respect to the tire widthwise direction,as shown in FIG. 31.

In the pattern shown in FIG. 31, the chamfered portion 32 is provided atopposite corners at the leading side and at the trailing side in thecenter blocks 18 a and in the second blocks 18 b, as in FIG. 18.

In FIG. 32, ground-contacting pressure of the pattern of FIG. 31 isshown. The higher the dot density of portions at the ground-contactingsurface is, the higher is the ground-contacting pressure, and the lowerthe dot density of portions at the ground-contacting surface is, thelower is the ground-contacting pressure.

TEST EXAMPLE 10

The pneumatic tire of Conventional Example 1 and the pneumatic tire ofExample 1, to which the invention was applied, were prepared, and noisewas measured using an indoor drum tester.

The test measured sound pressure (peaks of sound pressure waveforms)near the sides of the test tires at a speed of 80 km/hour.

In Test Example 1, a test was conducted with respect to a tire providedwith the tread pattern (monopitch) shown in FIG. 14.

The size of the test tires was 195/65R15. As the block size, dimension Awas 30 mm, dimension B was 20 mm, and dimension C was 10 mm (see FIG.13).

The width of the ground contact region in the shoulder blocks wasequivalent to dimension B (20 mm).

Tire of Conventional Example 1: a tire having no chamfered portionsformed thereon and in which the tread surface of the shoulder blocks wasflat (along the tire outer contour configuration) (see FIG. 30).

Tire of Example 1: a tire in which a chamfered portion was formed at acorner on the leading side of the shoulder block, as shown in FIG. 19.Dimensions and ratios were as listed below in Table 14. TABLE 14Dimension A 30 mm B 20 mm C 10 mm Ha 0.5 mm  Hb 0 La 15 mm Lb 25 mm Lc 0Ld 0 Le 0 Lf 0 Ratio Ha/C 0.05 Hb/C 0 La/B 0.75 Lb/A 0.83 Lc/A 0 Ld/B 0Le/B 0 Lf/B 0

In Table 14, 0 (mm) indicates that there had not been done anyprocessing corresponding to that dimension.

An index display, in which the size of the sound pressure waveform peakof the pneumatic tire of Conventional Example 1 was 100, was used forevaluation. The lower the numerical value, the lower was the noiselevel, indicating that the amount of noise generated was suppressed at alow level. The test results are shown in Table 15 below, and it will beunderstood that the noise level was sufficiently low in the tire ofExample 1. TABLE 15 Noise Level Conventional Example 1 100 Example 1 87

TEST EXAMPLE 11

The pneumatic tire of Conventional Example 1 and the pneumatic tire ofExample 2, to which the invention was applied, were prepared, and a testwas conducted in the same manner as in Test Example 1.

In Test Example 2, a test was conducted in a manner similar to TestExample 1 with respect to a tire provided with the tread pattern(monopitch) shown in FIG. 14, but only the configuration of the shoulderblocks was different.

Tire of Example 2: a tire having a chamfered portion formed at thetrailing edge of the shoulder block, as shown in FIG. 20. Dimensions andratios were as listed below in Table 16. TABLE 16 Dimension A 30 mm B 20mm C 10 mm Ha 0 Hb 0.5 mm  La 0 Lb 0 Lc 12 mm Ld  6 mm Le  7 mm Lf  7 mmRatio Ha/C 0 Hb/C 0.05 La/B 0 Lb/A 0 Lc/A 0.4 Ld/B 0.3 Le/B 0.35 Lf/B0.35

In Table 16, 0 (mm) indicates that there had not been done anyprocessing corresponding to that dimension.

The test results are shown in Table 17 below, and it will be understoodthat the noise level was sufficiently low in the tire of Example 2.TABLE 17 Noise Level Conventional Example 1 100 Example 2 87

TEST EXAMPLE 12

The pneumatic tire of Conventional Example 1 and the pneumatic tire ofExample 3, to which the invention was applied, were prepared, and a testwas conducted in the same manner as in Test Example 10.

In Test Example 3, a test was conducted in a manner similar to TestExamples 10 and 11 with respect to a tire provided with the treadpattern (monopitch) shown in FIG. 14, but only the configuration of theshoulder blocks was different.

Tire of Example 3: a tire having a chamfered portion formed at theleading side corner of the shoulder block and at the trailing edge ofthe shoulder block, respectively, as shown in FIG. 13. Dimensions andratios were as listed below in Table 18. TABLE 18 Dimension A 30 mm B 20mm C 10 mm Ha 0.5 mm  Hb 0.5 mm  La 15 mm Lb 25 mm Lc 12 mm Ld  6 mm Le 7 mm Lf  7 mm Ratio Ha/C 0.05 Hb/C 0.05 La/B 0.75 Lb/A 0.83 Lc/A 0.4Ld/B 0.3 Le/B 0.35 Lf/B 0.35

In Table 18, 0 (mm) indicates that there had not been done anyprocessing corresponding to that dimension.

The test results are shown in Table 19 below, and it will be understoodthat the noise level was even lower in the tire of Example 3 than in thepreceding Examples 1 and 2 due to two chamfered portions being disposed.TABLE 19 Noise Level Conventional Example 1 100 Example 3 77

TEST EXAMPLE 13

The pneumatic tire of Conventional Example 1 and the pneumatic tires ofExamples 4 to 11, to which the invention was applied, were prepared, anda test was conducted in the same manner as in Test Example 1.

In Test Example 4, a test was conducted in a manner similar to TestExample 10 with respect to a tire provided with the tread pattern(monopitch) shown in FIG. 14.

Tires of Examples 4 to 11: tires having a chamfered portion formed atthe leading side corner of the shoulder block, as shown in FIG. 19, withLa being fixed at 15 mm, Lb being fixed at 25 mm, and the dimension Habeing varied.

Dimensions and ratios, and the evaluation, were as listed in FIG. 21.

It will be understood from the test results that, in order tosufficiently reduce noise level, it is best for Ha to be 0.2 to 2.5 mmand for Ha/C to be 0.02 to 0.25.

TEST EXAMPLE 14

The pneumatic tire of Conventional Example 1 and the pneumatic tires ofExamples 12 to 19, to which the invention was applied, were prepared,and a test was conducted in the same manner as in Test Example 10.

In Test Example 14, a test was conducted in a manner similar to TestExample 10 with respect to a tire provided with the tread pattern(monopitch) shown in FIG. 14.

Tires of Examples 12 to 19: tires having a chamfered portion formed atthe trailing side of the shoulder block, as shown in FIG. 20, with Lcbeing fixed at 12 mm, Ld being fixed at 6 mm, Le being fixed at 7 mm, Lfbeing fixed at 7 mm, and the dimension Hb being varied.

Dimensions and ratios, and the evaluation, were as listed in FIG. 22.

It will be understood from the test results that, in order tosufficiently reduce noise level, it is best for Hb to be 0.2 to 2.5 mmand for Hb/C to be 0.02 to 0.25.

TEST EXAMPLE 15

The pneumatic tire of Conventional Example 1 and pneumatic tires ofExamples 20 to 26, to which the invention was applied, were prepared,and a test was conducted in the same manner as in Test Example 10.

In Test Example 15, a test was conducted in a manner similar to TestExample 10 with respect to a tire provided with the tread pattern(monopitch) shown in FIG. 14.

Tires of Examples 20 to 26: tires having a chamfered portion formed atthe leading side corner of the shoulder block, as shown in FIG. 19, withLb being fixed at 25 mm, Ha being fixed at 0.5 mm, and the dimension Labeing varied.

Dimensions and ratios, and the evaluation, were as listed in FIG. 23.

It will be understood from the test results that, in order tosufficiently reduce noise level, it is best for La to be 0.2 to 2.5 mmand for La/B to be 0.02 to 0.25.

TEST EXAMPLE 16

The pneumatic tire of Conventional Example 1 and pneumatic tires ofExamples 27 to 30, to which the invention was applied, were prepared,and a test was conducted in the same manner as in Test Example 1.

In Test Example 16, a test was conducted in a manner similar to TestExample 10 with respect to a tire provided with the tread pattern(monopitch) shown in FIG. 14.

Tires of Examples 27 to 30: tires having a chamfered portion formed atthe leading side corner of the shoulder block, as shown in FIG. 19, withLa being fixed at 15 mm, Ha being fixed at 0.5 mm, and the dimension Lbbeing varied.

Dimensions and ratios, and the evaluation, were as listed in FIG. 24.

It will be understood from the test results that, in order tosufficiently reduce noise level, it is best for Lb to be 10 mm orgreater and for Lb/A to be 0.3 or greater.

TEST EXAMPLE 17

The pneumatic tire of Conventional Example 1 and pneumatic tires ofExamples 31 to 35, to which the invention was applied, were prepared,and a test was conducted in the same manner as in Test Example 10.

In Test Example 17, a test was conducted in a manner similar to TestExample 10 with respect to a tire provided with the tread pattern(monopitch) shown in FIG. 14.

Tires of Examples 31 to 35: tires having a chamfered portion formed atthe leading side corner of the shoulder block, as shown in FIG. 19, withLd being fixed at 6 mm, Le being fixed at 7 mm, Lf being fixed at 7 mm,Hb being fixed at 0.5 mm, and the dimension Lc being varied.

Dimensions and ratios, and the evaluation, were as listed in FIG. 25.

It will be understood from the test results that, in order tosufficiently reduce noise level, it is best for Lc to be 5 mm to 25 mmand for Lc/A to be 0.17 to 0.83.

TEST EXAMPLE 18

The pneumatic tire of Conventional Example 1 and pneumatic tires ofExamples 31 to 35, to which the invention was applied, were prepared,and a test was conducted in the same manner as in Test Example 10.

In Test Example 18, a test was conducted in a manner similar to TestExample 10 with respect to a tire provided with the tread pattern(monopitch) shown in FIG. 14.

Tires of Examples 36 to 40: tires having a chamfered portion formed atthe trailing side of the shoulder block, as shown in FIG. 20, with Lcbeing fixed at 12 mm, Le being fixed at 7 mm, Lf being fixed at 7 mm, Hbbeing fixed at 0.5 mm, and the dimension Ld being varied.

Dimensions and ratios, and the evaluation, were as listed in FIG. 26.

It will be understood from the test results that, in order tosufficiently reduce noise level, it is best for Ld to be 3 mm to 15 mmand for Ld/B to be 0.15 to 0.75.

TEST EXAMPLE 19

The pneumatic tire of Conventional Example 1 and pneumatic tires ofExamples 41 to 45, to which the invention was applied, were prepared,and a test was conducted in the same manner as in Test Example 10.

In Test Example 19, a test was conducted in a manner similar to TestExample 10 with respect to a tire provided with the tread pattern(monopitch) shown in FIG. 14.

Tires of Examples 41 to 45: tires having a chamfered portion formed atthe trailing side of the shoulder block, as shown in FIG. 20, with Ldbeing fixed at 6 mm, Lc being fixed at 12 mm, Lf being fixed at 7 mm, Hbbeing fixed at 0.5 mm, and the dimension Le being varied.

Dimensions and ratios, and the evaluation, were as listed in FIG. 27.

It will be understood from the test results that, in order tosufficiently reduce noise level, it is best for Le to be 2 mm to 15 mmand for Le/B to be 0.10 to 0.75.

TEST EXAMPLE 20

The pneumatic tire of Conventional Example 1 and pneumatic tires ofExamples 46 to 50, to which the invention was applied, were prepared,and a test was conducted in the same manner as in Test Example 10.

In Test Example 20, a test was conducted in a manner similar to TestExample 10 with respect to a tire provided with the tread pattern(monopitch) shown in FIG. 14.

Tires of Examples 46 to 50: tires having a chamfered portion formed atthe trailing side of the shoulder block, as shown in FIG. 20, with Ldbeing fixed at 6 mm, Lc being fixed at 12 mm, Le being fixed at 7 mm, Hbbeing fixed at 0.5 mm, and the dimension Lf being varied.

Dimensions and ratios, and the evaluation, were as listed in FIG. 28.

It will be understood from the test results that, in order tosufficiently reduce noise level, it is best for Lf to be 2 mm or greaterand for Lf/B to be 0.10 or greater.

TEST EXAMPLE 21

The pneumatic tire of Conventional Example 2 and a pneumatic tire ofExample 51, to which the invention was applied, were prepared, and atest was conducted in the same manner as in Test Example 10.

In Test Example 21, a test was conducted in a manner similar to TestExamples 10 and 11 with respect to a tire provided with the treadpattern shown in FIG. 29A.

The size of the tires was 195/65R14.

As for the size of blocks 18, dimension A was 30 mm, dimension B was 25mm, and the height was 10 mm. Regarding the shoulder block 18 c, thewidth of the ground-contacting region thereof corresponded to thedimension B (25 mm).

Lug grooves 16 were slanted at 40° with respect to the tire widthwisedirection.

A width D of a rib 19 on the tire equatorial plane CL was 13 mm.

Tires of Conventional Example 2: a tire in which the tread surface ofthe shoulder blocks 18 c was flat (along the tire outer contourconfiguration) and having no chamfered portion formed on the shoulderblocks 18 c.

Tire of Example 51: a tire having a first chamfered portion 24 formed atthe trailing side corner of the end edge 18D on the tire equatorialplane side of the shoulder block 18 c and a second chamfered portion 28formed at the leading edge, as shown in FIG. 29B.

Dimensions and ratios, and the evaluation, were as listed below in Table20. TABLE 20 Dimension A 30 mm B 25 mm C 10 mm Ha 0.5 mm  Hb 0.5 mm  La18.75 mm   Lb 25 mm Lc 12 mm Ld 7.5 mm  Le 8.75 mm   Lf 8.75 mm   RatioHa/C 0.05 Hb/C 0.05 La/B 0.75 Lb/A 0.83 Lc/A 0.4 Ld/B 0.3 Le/B 0.35 Lf/B0.35

The test results are shown in Table 21 below, and it will be understoodthat there arise superior effects by the configuration of the presentinvention as described above, in a tire of a pattern where the luggrooves are slanted with respect to the tire widthwise direction. TABLE21 Noise Level Conventional Example 2 100 Example 51 81

Industrial Applicability

As described above, the pneumatic tire relating to the present inventionis suitable for use in automobiles and suitable for reducing tire noisewithout compromising other characteristics.

1. A pneumatic tire including a tread having plural blocks divided byplural grooves that mutually intersect, characterized in that: height ofeach block at the leading side edge thereof varies in a tire widthwisedirection, a portion of the leading side edge that initially contacts aroad surface being a “highland” portion which is positioned on a tireradial-direction outer side than the remaining portion of the leadingside edge that later contacts the road surface; and the highland portionextends in a tire circumferential direction and the position of thehighland portion in the tire widthwise-direction is changed in the tirecircumferential direction.
 2. A pneumatic tire including a tread havingplural blocks divided by plural grooves that mutually intersect,characterized in that: height of each block at the trailing side edgethereof varies in a tire widthwise direction, a portion of the trailingside edge that lastly separates from a road surface being a “highland”portion which is positioned on a tire radial-direction outer side thanthe remaining portion of the trailing side edge that initially separatesfrom the road surface; and the highland portion extends in a tirecircumferential direction and the position of the highland portion inthe tire widthwise-direction is changed in the tire circumferentialdirection.
 3. A pneumatic tire including a tread having plural blocksdivided by plural grooves that mutually intersect, characterized inthat: each of leading side edges and trailing side edges of the blockshas a height that differs in a tire widthwise direction; a portion ofthe leading side edge that initially contacts a road surface being afirst “highland” portion which is positioned on a tire radial-directionouter side than the remaining portion of the leading side edge thatlater contacts the road surface; and a portion of the trailing side edgethat lastly separates from a road surface being a second “highland”portion which is positioned on a tire radial-direction outer side thanthe remaining portion of the trailing side edge that initially separatesfrom the road surface, wherein each of the first highland portion andthe second highland portion extends in a tire circumferential directionand the position of the highland portion in the tire widthwise-directionis changed in the tire circumferential direction.
 4. The pneumatic tireof claim 3, wherein the first highland portions and the second highlandportions are connected such that they are continuous in the tirecircumferential direction.
 5. The pneumatic tire of claim 1, whereinportions lower than the highland portions are formed as smoothly curvedsurfaces whose height gradually decreases towards block edges.
 6. Thepneumatic tire of claim 1, wherein when the blocks are viewed in crosssection along the tire widthwise direction, the highland portions andthe portions lower than the highland portions are provided in anyportions at tire circumferential-direction positions.
 7. The pneumatictire of claim 1, wherein in a tread surface of the blocks, the highlandportions include flat portions that coincide with an outer contourconfiguration of the tire.
 8. The pneumatic tire of claim 7, wherein inthe block edges in the tire circumferential direction, a tirewidthwise-direction dimension of the flat portion is in a range of 3 mmto 15 mm (inclusive of 3 mm and 16 mm).
 9. The pneumatic tire of claim7, wherein in the block edges in the tire circumferential direction, thetire widthwise-direction dimension of the flat portion is 0.15 to 0.75times a tire widthwise-direction dimension of the block edges.
 10. Thepneumatic tire of claim 1, wherein in the block edges in the tirecircumferential direction, a depth dimension in a block height directionfrom a highest portion of the highland portion to a lowest portion ofthe tread surface is within a range of 0.1 mm to 2.5 mm (inclusive of0.1 mm and 2.5 mm).
 11. The pneumatic tire of claim 1, wherein in theblock edges in the tire circumferential direction, the depth dimensionin the block height direction from the highest portion of the highlandportion to the lowest portion of the tread surface is 0.01 to 0.25 timesa maximum height of the highland portion.
 12. The pneumatic tire ofclaim 1, wherein in the block edges in the tire circumferentialdirection, a tire widthwise-direction length of the portions lower thanthe highland portions is 5 mm to 17 mm (inclusive of 5 mm and 17 mm).13. The pneumatic tire of claim 1, wherein in the block edges in thetire circumferential direction, the tire widthwise-direction length ofthe portions lower than the highland portions is 0.25 to 0.85 times thetire widthwise-direction dimension of the block edges.
 14. The pneumatictire of claim 1, wherein in the block edges in the tirecircumferential-direction of blocks disposed at places other than on atire equatorial plane of the tread, highland portions are disposed at atire equatorial plane side.
 15. A pneumatic tire including a treadhaving plural blocks divided by plural circumferential grooves extendingin the tire circumferential direction and plural grooves that intersectthe circumferential grooves, characterized in that: at end edges, on thetire equatorial plane side, of blocks at outermost sides in a tirewidthwise direction, highland portions along a tire outer contour aredisposed at one of a leading side end edge and a trailing side end edge,and first lowland portions whose block height gradually becomes lower ina direction of moving away from the highland portions are disposed atthe other of the leading side end edge and the trailing side end edge,wherein, at ground-contact ends of the blocks at the outermost sides inthe tire widthwise direction, all are highland portions along the tireouter contour.
 16. A pneumatic tire including a tread having pluralblocks divided by plural grooves that mutually intersect, characterizedin that: highland portions along a tire outer contour and second lowlandportions that are lower than the highland portions and whose blockheight gradually becomes lower in a direction of moving away from thehighland portions are disposed at a leading side edge or a trailing sideedge of blocks at outermost sides in a tire widthwise direction.
 17. Apneumatic tire including a tread having plural blocks divided by pluralgrooves that mutually intersect, characterized in that: at end edges, ofthe tire equatorial plane side, of blocks at outermost sides in a tirewidthwise direction, highland portions along a tire outer contour aredisposed at one of a leading side end edge and a trailing side end edge,and first lowland portions whose block height gradually becomes lower ina direction of moving away from the highland portions are disposed atthe other of the leading side end edge and the trailing side end edge;and highland portions along a tire outer contour and second lowlandportions that are lower than the highland portions and whose blockheight gradually becomes lower in a direction of moving away from thehighland portions are disposed at the leading side edge or the trailingside edge of the blocks at the outermost sides in the tire widthwisedirection not provided with the first lowland portions.
 18. Thepneumatic tire of claim 15, wherein in the end edges on the tireequatorial plane side, of the blocks at outermost sides in the tirewidthwise direction, when Ha denotes a depth dimension in a block heightdirection from a highest portion of the highland portion to a lowestportion of the first lowland portion, Ha is 0.2 mm to 2.5 mm.
 19. Thepneumatic tire of claim 15, wherein in the end edges on the tireequatorial plane side, of the blocks at outermost sides in the tirewidthwise direction, when Ha denotes a depth dimension in a block heightdirection from a highest portion of the highland portion to a lowestportion of the first lowland portion and C denotes block height in theend edges, on the tire equatorial plane side, of the blocks at outermostsides in the tire widthwise direction, Ha/C is 0.02 to 0.25.
 20. Thepneumatic tire of claim 16, wherein in the leading side edge or trailingside edge provided with the second lowland portion, when Hb denotes adepth dimension in a block height direction from a highest portion ofthe highland portion to a lowest portion of the second lowland portion,Hb is 0.2 mm to 2.5 mm.
 21. The pneumatic tire of claim 16, wherein inthe leading side edge or trailing side edge provided with the secondlowland portion, when Hb denotes a depth dimension in a block heightdirection from a highest portion of the highland portion to a lowestportion of the second lowland portion and C denotes block height in theend edge, on the tire equatorial plane side, of the blocks at outermostsides in the tire widthwise direction, Hb/C is 0.02 to 0.25.
 22. Thepneumatic tire of claim 15, wherein when La denotes a dimension of thefirst lowland portion measured from the end edge on the tire equatorialplane side towards the tire widthwise-direction outer side, dimension Lais 5 mm or greater.
 23. The pneumatic tire of claim 15, wherein when Ladenotes a dimension of the first lowland portion measured from the endedge on the tire equatorial plane side towards the tirewidthwise-direction outer side and B denotes a dimension of the block atthe outermost side in the tire widthwise direction measured, in the tirewidthwise direction, from the end edge on the tire equatorial plane sideto the ground-contact edge on the tire widthwise-direction outer side,La/B is 0.25 or greater.
 24. The pneumatic tire of claim 15, whereinwhen Lb denotes a dimension of the first lowland portion measured alongthe tire circumferential direction from the leading side edge ortrailing side edge provided with the first lowland portion, Lb is 10 mmor greater.
 25. The pneumatic tire of claim 15, wherein when Lb denotesa dimension of the first lowland portion measured along the tirecircumferential direction from the leading side edge or trailing sideedge provided with the first lowland portion and A denotes a dimensionof the end edge on the tire equatorial plane side measured along thetire circumferential direction, Lb/A is 0.3 or greater.
 26. Thepneumatic tire of claim 16, wherein when P1 denotes a tirecircumferential-direction outermost end of the second lowland portionfurthest from the leading side edge or trailing side edge provided withthe second lowland portion in the tire circumferential direction and Lcdenotes a dimension measured along the tire circumferential directionfrom the tire circumferential-direction outermost end P1 to the leadingside edge or trailing side edge provided with the second lowlandportion, Lc is 2 mm to 25 mm.
 27. The pneumatic tire of claim 16,wherein when P1 denotes a tire circumferential-direction outermost endof the second lowland portion furthest from the leading side edge ortrailing side edge provided with the second lowland portion in the tirecircumferential direction, Lc denotes a dimension measured along thetire circumferential direction from the tire circumferential-directionoutermost end P1 to the leading side edge or trailing side edge providedwith the second lowland portion, and A denotes a dimension of the endedge on the tire equatorial plane side measured along the tirecircumferential direction, Lc/A is 0.17 to 0.83.
 28. The pneumatic tireof claim 16, characterized in that, in the leading side edge or trailingside edge of the block at the outermost side in the tire widthwisedirection provided with the second lowland portion, when Ld denotes adimension measured along the tire widthwise direction from an endportion, of the block, on the tire equatorial plane side to the secondlowland, Ld is 3 mm to 15 mm.
 29. The pneumatic tire of claim 16,wherein in the leading side edge or trailing side edge of the block atthe outermost side in the tire widthwise direction provided with thesecond lowland portion, when Ld denotes a dimension measured along thetire widthwise direction from an end portion, of the block, on the tireequatorial plane side to the second lowland and B denotes a dimension ofthe block at the outermost side in the tire widthwise directionmeasured, along the tire widthwise direction, from the end edge on thetire equatorial plane side to the ground-contact edge on the tirewidthwise-direction outer side, Ld/B is 0.15 to 0.75.
 30. The pneumatictire of claim 16, wherein when P1 denotes a tirecircumferential-direction outermost end of the second lowland portionfurthest from the leading side edge or trailing side edge provided withthe second lowland portion in the circumferential direction, P2 denotesan intersection between the leading side edge or trailing side edgeprovided with the second lowland portion and an imaginary straight lineFL that passes through the tire circumferential-direction outermost endP1 along the tire circumferential direction, and Le denotes a dimensionmeasured along the tire widthwise direction from the intersection P2 tothe end portion on the tire equatorial plane side of the second lowlandportion, Le is 2 mm to 15 mm.
 31. The pneumatic tire of claim 16,wherein when P1 denotes a tire circumferential-direction outermost endof the second lowland portion furthest from the leading side edge ortrailing side edge provided with the second lowland portion in thecircumferential direction, P2 denotes an intersection between theleading side edge or trailing side edge provided with the second lowlandportion and an imaginary straight line FL that passes through the tirecircumferential-direction outermost end P1 along the tirecircumferential direction, Le denotes a dimension measured along thetire widthwise direction from the intersection P2 to the end portion onthe tire equatorial plane side of the second lowland portion, and Bdenotes a dimension of the block at the outermost side in the tirewidthwise direction measured, in the tire widthwise direction, from theend edge on the tire equatorial plane side to the ground-contact edge onthe tire widthwise-direction outer side, Le/B is 0.1 to 0.75.
 32. Thepneumatic tire of claim 16, wherein when P1 denotes a tirecircumferential-direction outermost end of the second lowland portionfurthest from the leading side edge or trailing side edge provided withthe second lowland portion in the circumferential direction, P2 denotesan intersection between the leading side edge or trailing side edgeprovided with the second lowland portion and an imaginary straight lineFL that passes through the tire circumferential-direction outermost endP1 along the tire circumferential direction, and Lf denotes a dimensionmeasured along the tire widthwise direction from the intersection P2 tothe tire widthwise-direction outer side end of the second lowlandportion, Lf is 2 mm or greater.
 33. The pneumatic tire of claim 16,wherein when P1 denotes a tire circumferential-direction outermost endof the second lowland portion furthest from the leading side edge ortrailing side edge provided with the second lowland portion in thecircumferential direction, P2 denotes an intersection between theleading side edge or trailing side edge provided with the second lowlandportion and an imaginary straight line FL that passes through the tirecircumferential-direction outermost end P1 along the tirecircumferential direction, Lf denotes a dimension measured along thetire widthwise direction from the intersection P2 to the tirewidthwise-direction outer side end of the second lowland portion, and Bdenotes a dimension of the block at the outermost side in the tirewidthwise direction, measured from the end edge on the tire equatorialplane side to the ground-contact edge on the tire widthwise-directionouter side, Lf/B is 0.1 or greater.
 34. The pneumatic tire of claim 15,wherein when the block at the outermost side in the tire widthwisedirection is viewed in cross section along the tire widthwise direction,the highland portion and the lowland portion are provided in any portionin the tire circumferential direction, in a cross-sectional view. 35.The pneumatic tire of claim 15, wherein in the block at the outermostside in the tire widthwise direction, the highland portion includes aflat portion that coincides with a tire outer contour configuration.